INFLUENCE OF NUTRITION ON PERFORMANCE, PRODUCT QUALITY AND

IMMUNOCOMPETENCE IN ORGANIC PIG PRODUCTION

Proefschrift ter verkrijging van de graad van

Doctor in de Diergeneeskundige Wetenschappen (PhD)

aan de Faculteit Diergeneeskunde, Universiteit Gent, 2004

Sam Millet

Promotor: Prof. dr. ir. G.P.J. Janssens

Vakgroep Dierenvoeding, Dierlijke Genetica, Vee-uitbating en Ethologie

Heidestraat 19, B-9820 Merelbeke

1

TABLE OF CONTENTS

List of Abbreviations …………………………………………………………………… 5

Chapter I. Introduction

I.A. Rationale and literature review …………………………………………………… 7

I.A.1. Organic pig fattening: possibilities and difficulties .….....……………………….... 9

I.A.2. Welfare, performance and meat quality of fattening pigs in alternative housing and

management systems: A review ....…………………..………………………………...…. 19

I.B. Aims and outline of the thesis …...…...……………………………………………. 39

Chapter II. Dietary protein in organic pig nutrition

Dietary protein for ad libitum fed organic fattening pigs ....……….….…………..……... 43

II.1. Introduction …………………………………………………………………….... 44 II.2. Material and Methods ……………………………………………………………. 44 II.2.1. Animals and management ……………………………………………………. 44 II.2.2. Feed …………………………………………………………………………... 45 II.2.3. Slaughtering ………………………………………………………………….. 47 II.2.4. Measurements ………………………………………………………………... 48 II.2.5. Statistical analysis ……………………………………………………………. 49

II.3. Results …..……………………………………………………………………….. 50 II.4. Discussion ……………………………………………………………………….. 52

II.4.1. Production parameters ………………………………………………………... 53 II.4.2. Meat and carcass parameters …………………………………………………. 55

II.5. Conclusion ……………………………………………………………………….. 56 Chapter III. Organic versus conventional nutrition in an organic and a conventional pig

fattening system

III.A. Performance, meat and carcass traits ……………………………………….…. 59

III.A.1. Effects of organic versus conventional housing and nutrition from birth until

slaughtering in a cross of traditional pig breeds ....……..…………………..……………. 61

III.A.1.1. Introduction ...………………………………………………………………. 62 III.A.1.2. Material and Methods ……………………………………………………… 62

III.A.1.2.1. Animals and management ………………………………………………. 62 III.A.1.2.2. Housing …………………………………………………………………. 63 III.A.1.2.3. Feed ……………………………………………………………………... 64 III.A.1.2.4. Measurements …...……………………………………………………… 66

III.A.1.2.5. Statistical analysis ...……………………………………………………… 68 III.A.1.3. Results ……………………………………………………………………… 69

2

III.A.1.3.1. Production characteristics ………………………………………………. 69 III.A.1.3.2. Carcass composition and meat quality ………………………………….. 69 III.A.1.3.3. Digestibility …………………………………………………………….. 73

III.A.1.4. Discussion ………………………………………………………………….. 74 III.A.1.5. Conclusion ………………………………………………………………….. 77

III.A.2. Effects of organic versus conventional housing and nutrition from weaning until slaughtering in terminal crossbreeds .…………………………………………………….. 79

III.A.2.1. Introduction ...…………………………………………………………….… 80 III.A.2.2. Material and Methods ...………………………………………………….… 80

III.A.2.2.1. Animals and management ………………………………………………. 80 III.A.2.2.2. Housing …………………………………………………………………. 81 III.A.2.2.3. Feed ……………………………………………………………………... 82 III.A.2.2.4. Slaughtering …………………………………………………………….. 82 III.A.2.2.5. Measurements …………………………………………………………... 84 III.A.2.2.6. Statistical analysis ………………………………………………………. 86

III.A.2.3. Results ...………………………………………………………………….… 86 III.A.2.4. Discussion ...………………………………………………………………... 90 III.A.2.5. Conclusion ………………………………………………………….……..... 91

III.B. Immunocompetence and selected metabolic properties ...…………...………… 93 Immunocompetence of fattening pigs fed organic versus conventional diets in organic versus conventional housing ...…………………………………………...…………………….... 95

III.B.1. Introduction ...…………………………………………………….…………... 96 III.B.2. Material and Methods …………………………………………..…………….. 97

III.B.2.1. Animals and management ...…………………………………………….… 97 III.B.2.2. Housing ...……………………………………………………………….… 97 III.B.2.3. Nutrition ...………………………………………………………………… 98 III.B.2.4. Measurements ...…………………………………………………………... 98 III.B.2.5. Statistics ...………………………………………………………………… 99

III.B.3. Results ...………………………………………………………………….…... 100 III.B.3.1. Thyroglobulin-specific antibodies ...……………………………………… 100 III.B.3.2. Haptoglobin ……………………………………………………………….. 100 III.B.3.3. Lactate …………………………………………………………………….. 102

III.B.4. Discussion ...………………………………………………………………….. 102 III.B.5. Conclusion ……………………………………………………………………. 104

Chapter IV. Application of corn cob mix in organic pig fattening

IV.A. Evaluation of Corn Cob Mix in organic finishing pig nutrition on performance

and product quality ……………..…….………………………………………………… 107

IV.A.1. Introduction ...………………………………………………………………… 108 IV.A.2. Material and methods ………………………………..……………………….. 108

IV.A.2.1. Animals and management ………………………………………………… 109 IV.A.2.2. Feed composition …………………………………………….…………… 110 IV.A.2.3. Measurements …………………………………………………………….. 113 IV.A.2.4. Statistical analysis ……………………………………………………….... 114

IV.A.3. Results ..………………………………………………………………………. 114 IV.A.3.1. Experiment CCM1 ………………………………………………………... 114

3

IV.A.2.2. Experiment CCM2 ………………………………………………………... 116 IV.A.4. Discussion ……………………………………………………………………. 118 IV.A.5. Conclusion ...…………………………………………………………………. 120

IV.B. Effect of CCM inclusion on immunocompetence in organically fed finishing

pigs...……………………….………………………………………………………….…... 121

IV.B.1. Introduction ..……………………….…………………………….…………... 122 IV.B.2. Material and methods .……………………….…………………………….…. 122

IV.B.2.1. Animals and management .…………………….………………………….. 122 IV.B.2.2. Feed composition ……………………….…………………………….…... 123 IV.B.2.3. Measurements .....……………………….…………………………….…... 124 IV.B.2.4. Statistical analysis .……………………….…………………………….…. 125

IV.B.3. Results .……………………….…………………………….………………… 125 IV.B.4. Discussion ...……………………….…………………………….…………… 128 IV.B.5. Conclusion ……………………….…………………………….…………….. 129

Chapter V. General discussion .....……………………………………………………... 131

Summary …………...………………………………...………………………………….. 139

Samenvatting ……..…………………………………….……………………………….. 143

References ...………………………………………….………………………………….. 147

Dankwoord ...………………...………….…………………………….……………….... 163

Curriculum vitae ………………...………………….………………………….……….. 165

4

5

LIST OF ABBREVIATIONS

ADFI Average daily feed intake

ADG Average daily growth

AFB1 Aflatoxin B1

ALA Alfa linolenic acid

ATP Adenosine triphosphate

App Actinobacillus pleuropneumoniae

BSE Bovine spongifom encephalopathy

BW Body weight

CCM Corn cob mix

CF Conventional feed

CGM Capteur Gras-Maigre, classification apparatus

CH Conventional housing

CIE a* Redness

CIE b* Yellowness

CIE L* Lightness

DE Digestible energy

DFD Dark, firm, dry

DL Danish Landrace

DON Deoxynivalenol

DP Ileal digestible phosphorus

EC Council of the European Union

EU European Union

FB1 Fumonisin B1

FB2 Fumonisin B2

FB3 Fumonisin B3

FCR Feed conversion ratio

GMO Genetically modified organism

HP High protein feed

ID CYS Ileal digestible cysteine

ID LYS Ileal digestible lysine

ID MET Ileal digestible methionine

6

ID THR Ileal digestible threonine

ID TRP Ileal digestible tryptophan

Ig Immunoglobulin

IL Interleucin

i.m. Intramuscularly

IMF Intramuscular fat content

ISO International Organization for Standardization

IU International unit

L:E Ileal digestible lysine to net energy ratio

LP Low protein feed

LT Musculus longissimus thoracis et lumborum

MD Ministrial Decree

ME Metabolisable energy

MP Medium protein feed

NEv Net energy for production in pigs according to the dutch CVB system 1998

nn Homozygous stress positive

Nn Heterozygous stress negative

NN Homozygous stress negative

NRC National research council

OF Organic feed

OH Organic housing

OTA Ochratoxin A

pH1 pH at 40 minutes post mortem

pH2 pH at 24 houres post mortem

PQM Pork Quality Meter, electrical conductivity

PSE Pale, soft, exudative

RD Royal Decree

SKGII Slachtkörper Klassifizierung Gerät, classification apparatus

TBARS 2-thiobarbituric acid reactive substances

SM Musculus semimembranosus

TL Total livestock

TNF Tumor necrosis factor

WHO World Health Organisation

ZEA Zearalenone

7

CHAPTER I. INTRODUCTION

I.A. RATIONALE AND LITERATURE REVIEW

This chapter combines two reviews.

First, the organic pig fattening is situated within the framework of opportunities and

difficulties. A second part gives a review on welfare, performance and meat quality aspects in

alternative pig production systems.

8

9

I.A.1. ORGANIC PIG FATTENING: POSSIBILITIES AND DIFFICULTIES

ABSTRACT

Although organic pig production forms a niche market, interest in organic production has

increased. Consequently, there is a growing demand for scientific information. In this review,

difficulties and opportunities of organic livestock production are discussed, considering well-

being, health, environmental concerns, nutrition, performance and financial aspects.

After:

S. Millet, G.P.J. Janssens, M. Hesta, R. De Wilde, 2001. Biologische vleesvarkensteelt,

mogelijkheden en moeilijkheden. Vlaams Diergeneeskundig Tijdschrift 70, 271-278.

10

INTRODUCTION

The organic agriculture forms a small percentage of the total agricultural production, but it is

characterised by a steep growth over the last decade.

Several factors in conventional production convince consumers to switch to products of

organic agriculture. Overproduction in the EU, the excessive use of agrochemicals,

Salmonella, swine fever, BSE and dioxins scare people away from conventional meat

production. Popular media often link practices and abuses in conventional farming to

environmental and health concerns.

It is time to evaluate whether organic agriculture is able to give an alternative. Some years

ago, unbiased information on this type of production was scarce. Scientific literature on

zootechnical performances in organic production is limited. Furthermore, some reports might

be biased in either way, which makes a careful evaluation necessary.

LEGISLATION

Legislation on organic farming is based on Council Regulation (EEC) 2092/91(Council of the

European Union, 1991), which was supplemented to include livestock production with

Council Regulation (EC) 1804/99 (Council of the European Union, 1999). Belgian legislation

was based on these regulations and translated to the Royal Decree (RD) of April 17th, 1992,

which was amended by the RD of July 10th, 1998, and the Ministrial Decree (MD) of October

30th, 1998, which in turn was amended by MD of August, 19th, 2000.

This legislation provides strict rules for the production process, aimed at securing the

principles of organic farming. It includes concerns about the environment, production of safe

and healthy food, and animal welfare.

Figure I.1 Official Belgian and European logos for organically produced products

11

Although having a legislation drastically limits the method of farming, it can also be seen as a

protective measure, as everyone who wants to sell organic products has to meet the legal

standards (de Jonge and Goewie, 2000). Of course, strict supervision should be excercised to

ensure that the regulations are respected . Accredited inspection organisations are responsible

(MD of August 17th, 1997). For Belgium, these organisations are BLIK and ECOCERT. Meat

that is produced in a certificated way receives a label (figure I.1).

WELFARE

In organic pig fattening, specific housing measures are taken to meet ethological demands of

the animals. Pigs in an organic barn must have access to an outdoor area and they should have

more space allowance. Space requirements are expressed in relation to the live weight of the

pigs, e.g. finishing pigs must have access to an indoor area of at least 1.3m²/pig and an

outdoor area of 1m²/pig (Council of the European Union, 1999). A dry resting area with a

sufficient amount of litter has to be provided. Economical concerns emerge as the number of

animals that can be kept in such a way is limited and because of the more labour-intensive

way of production.

Physical castration is allowed in order to maintain the product quality and traditional

production practices but the surgery must be carried out at the most appropriate age by

qualified personnel and any suffering to the animals must be reduced to a minimum (Council

of the European Union, 1999).

HEALTH

Prevention of disease in organic livestock production relies on the selection of appropriate

breeds or strains, the application of animal husbandry practices appropriate for the specific

needs of each species, enhancing the immune responsiveness of the animal and ensuring an

appropriate density of livestock. The preventive use of chemically synthesised allopathic

medicinal products is not permitted in organic farming, with exception of treatments that are

compulsory under national or community legislation, like vaccination against Aujeszky’s

disease. Individual treatment of an animal is allowed and should be performed by a qualified

veterinarian. In order to ensure meat free from residues, the withdrawal period used in

conventional practices is doubled, with a minimum of 48 hours (MD of October, 30th, 1998).

12

Pigs with an outdoor area are more susceptible to parasitic diseases (Nansen and Roepstorff,

1999). Research has been done looking into the biological control of parasites using

microfungi. Mixing a daily dose of the microfungus Duddingtonia flagrans in the feed of

experimentally infected pasture-reared pigs led to lowered herbage larval infectiveness of

Oesophagostomum dentatum and Hyostrongylus rubidus. However, these are parasites that

are infectious as larvae. For the control of nematodes of which the eggs are infectious, like

Ascaris suum, ovicidic fungi will be needed. To this date, we have not seen any profound

studies investigating the latter (Thamsborg et al., 1999).

A Swedish slaughterhouse survey (Hansson et al., 2000) revealed a lower percentage of

animals displaying tail biting (0.5 versus 1.4 %), or showing abscesses (0.5 versus 1.5%),

pleuritis (1.8 versus 7.4%), and white spots (4.1 versus 5.6%) in organic versus conventional

pig farming. The incidence of joint diseases such as arthritis (2.1 versus 1.3%) and arthrosis

(1.5 versus 0.4%) was higher in the organically reared pigs. Hansson et al. (2000) ascribed the

difference in abscesses to the reduction of tail biting on the one hand and on the other hand to

a smaller number of injection sites (where pathogens may be introduced) caused by a decrease

in the use of preventive medications like injections with iron dextrane or routine deworming.

The fact that there were less organically farmed animals with white spots might be due to a

higher percentage of lesions that had already healed. The latter might be due to an earlier

infection or a longer fattening period. However, as this was a slaughterhouse survey, small

lesions were probably not detected. In an Austrian study on organic farms, the percentages of

white spots and pneumonia lesions were much higher (49.9 and 24.2%), probably because of

a more intensive research. In comparison with the prevalences on conventional farms,

conclusions were comparable with those of Hansson et al. (2000).

NUTRITION

Organic agriculture intends to be a sustainable agriculture, thus using feedstuffs that are

obtained locally.

A list of feed ingredients that are allowed in organic farming was compiled and included in

the legislation. Only products of organic agricultural production are admitted (MD of august

19th, 2000). However, as it is still often difficult to find sufficient ingredients to formulate a

well-balanced diet, the use of a small number of conventional feed components (table I.1) is

temporarily sustained but the ingredients cannot represent more than 20% of the feed.

13

When considering nutritional requirements, the fact that pigs can benefit from an outdoor area

suggests a higher maintenance energy requirement, as the energy required for activity and

thermoregulation will increase (Enfält et al., 1997; Thielen and Kienzle, 1994). Allopathic

growth promoting agents are not allowed, which will also be the case in future conventional

pig nutrition. A main characteristic of organic feed formulation is that no synthetic amino

acids are allowed. This results in a number of problems: the competition with human nutrition

for certain feedstuffs, a higher feeding cost due to the use of protein sources, and the

availability of ingredients that are not genetically modified organisms (GMO). An opportunity

is that certain by-products of the human organic feed industry can be used (Wlcek and

Zollitsch, 2000).

Table I.1 Conventional feed ingredients allowed in organic agriculture following Belgian legislation (MD

August, 19th, 2000)

Wheat gluten

Maize gluten

Malt sprouts

Brewer’s grains

Toasted soy bean

Linseed

Linseed expellers

Potato protein

Fodder beet

Molasses as binding agent in compound feeds

Seaweed

Cod liver oil, non refined

In practice, some problems concerning the nutrition of organic livestock appear. In a German

field study, deficiencies in protein and essential amino acids were detected, together with

mineral imbalances, like sodium, zinc and selenium deficiencies. Moreover, vitamin E

deficiencies and poor feeding hygiene were noted, leading to clinical symptoms of

parakeratosis, behavioural problems and diarrhoea (Hennig, 1998; Kienzle et al., 1993;

Thielen and Kienzle, 1994). However, certain farms did not encounter such problems, which

indicates that with proper management, animal well-being as well as an adequate nutrition can

be achieved in organic pig fattening (Thielen and Kienzle, 1994).

14

ZOOTECHNICAL PERFORMANCE AND PRODUCT QUALITY

Sundrum et al. (2000b) stated that organic pig fattening leads to a more heterogenous growth

rate, which can represent a problem in scientific research and in practical circumstances.

Because of the high variability in growth and carcass parameters, it might be difficult to

obtain statistically significant results. This heterogeneity is also an additional hurdle when

commercialising.

Differences in performance as well as in meat and carcass characteristics result from

differences in feeding regime. Hansson et al. (2000) and Enfält et al. (1997) found a slower

daily gain in organic pig production and outdoor production due to a higher energy

expenditure from increased activity. According to Sundrum et al. (2000a), the ban on

synthetic amino acids affects growth, meat and carcass characteristics: organic feeds with a

lack of amino acids cause a slower daily gain and consequently result in a longer period

before reaching slaughter weight. The authors stated that the requirements could be met by

supplementing qualitative protein sources, like potato protein.

In their experiment, however, individually housed pigs were used, which is not the case in

organic farming. The amount of amino acids needed in organic pig fattening forms an

interesting topic. Chiba et al. (1991) showed a positive correlation between lysine

concentration in the feed and daily growth per unit of digestible energy of conventional pigs

between 20 and 50 kg. However, lysine intake per kg body weight gain was lower in diets

with a lower lysine to digestible energy ratio. If growth is slowed in organic farming due to a

higher maintenance energy requirement the question rises whether feeds with lowered protein

content can be used in organic pig fattening. Only limited differences were detected in meat

quality. Sundrum et al. (2000a) detected a significantly higher meat percentage in pigs

receiving feeds supplemented with amino acids, in contrast to organic diets without synthetic

amino acids. Nevertheless, in the pigs that consumed a diet low in essential amino acids, a

higher intramuscular fat content was detected, which might improve meat quality traits

(Fernandez et al., 1999b).

ENVIRONMENT

Nitrogen (N) balances in organic pig production cannot be evaluated unambiguously. The ban

on synthetic amino acids urges for a higher protein content, and the ban on growth promoting

agents (Lindermayer and Propstmeier, 1994) suggests a higher nitrogen emission per animal,

which is noxious to the environment. According to Bikker (2002), amino acid requirements

15

rise with the ban on antibiotic growth promoters. On the one hand, provision of straw can lead

to a higher NH3-emission, due to an increase of the emitting surface (Oude Groeniger and

Groenestein, 2000). On the other hand, Kirchmann and Witter (1989) stated that increasing

the amount of straw provided would lead to a lower ammonia volatilisation under aerobic

conditions, because it binds nitrogen in an organic form. The lower stocking density will lead

to lower manure production and thus decreases nitrogen emission in relation to area. This is

consistent with Danish research (Dalgaard et al., 1998). In that, organic pig production

resulted in a lower N-surplus per hectare but also a lower N-efficiency and a higher N-surplus

per kg meat than in conventional pig production. Careful consideration should also be given

to pen and barn construction as this can limit nitrogen emission in organic farming (Oude

Groeniger and Groenestein, 2000).

Manure from organic pig farms has to be used on organic farming land. However, in organic

vegetable production, the use of manure of organic livestock production is currently not

imposed. A maximum of 170 kg nitrogen per ha is allowed (Council of the European Union,

1999).

No research results on phosphorus (P) emission have been published so far. The enzymes

used in conventional pig production are allowed in organic production, in the case that they

are not of GMO-origin (Council of the European Union, 1999). Hence, most phytases cannot

be used, although they could lead to a better P-efficiency per kg of meat. However, as with

nitrogen, the P-emission per hectare might be lower in organic pig fattening due to a lower

stocking density.

ECONOMY

A major hurdle for organic production is the prime cost. An increase in prices by 30% is the

minimum to be able to compensate the higher feeding cost (Sundrum et al., 2000a). A lower

stocking density, a hypothesized longer fattening period and labour-intensive production

together with the cost for inspection agencies are other factors that increase the price. On the

other hand, costs for infrastructure e.g., heating, will be lower. For the consumer, an extra cost

of 30% will be a breaking point (Haest, 1999). If the increase is greater, consumers become

far less willing to pay . This constitutes a major problem, as feeding costs already elicit a price

raise of 30%. Dutch research calculated a cost of € 2,44/kg (Hoste et al., 2000). However,

they found that a lot of variation exists between farms. Research is needed to reduce the costs.

An accurate feeding regime that lowers feeding costs would be helpful.

16

The way of commercialisation can be a useful tool as well. Sale of the meat directly from

farmer to consumer will enhance both the confidence of the consumer and the profit margin of

the farmer.

Despite the financial concerns, organic production has become ever more popular over the

last decade (figure I.2). Considerable differences between countries exist. In 2000, in Austria

and Liechtenstein, 10 and 17% of farming area was organic, versus 0.3% in Poland, and even

less in other East European countries (Willer and Yussefi, 2000).

Organic farming in Belgium, and especially organic pig farming, represents a very small

percentage of the market. In 2002, 4753 organic fattening pigs, or 0.08% of total livestock

production, were slaughtered in Belgium (table I.2), whereas the total area of land under

organic agriculture is 1.45% of the total agricultural area (Willer and Richter, 2004). In 2001

and 2002, there was somewhat of a decrease in the number of organic pigs. Problems in the

Belgian organic pig production are the intensity of the conventional pig production, the lack

of cropland and the fear that the legislation on mineral excretion will make it difficult to

return to conventional agriculture after a decline in the number of animals. However,

commercialisation of the meat is already regulated in a way that provides a minimum degree

of price assurance.

Figure I.2 Increase in European organic farming during the last decade (source:Willer and Richter, 2004)

17

CONCLUSION

Organic pig production covers a niche market, but represents an alternative for the increasing

number of people that has become aversive to conventional meat. Organic pig meat

production has to overcome several difficulties and there is a clear need for scientific

information.

Organic farming leads to an increase in production costs, which will have to be recovered by

an increase in meat prices. The consumer will have to pay for a production system that

emphasizes animal well-being and is concerned about the environment. Many people might

buy organic meat because of the healthiness, but scientific evidence for this statement is not

given at the moment (van Vliet and Goewie, 1999). It all starts with the definition of health:

“A state of complete physical, mental and social well-being and not merely the absence of

disease or infirmity” (WHO). As there is not much scientific information on the healthiness

of organic food, the image of organic food as a healthy food will rather be a perception of the

consumer than a scientifically proven fact.

To gain and maintain the confidence of consumers, organic production will have to be

transparant. The recent legislation on production processes, control organisations and the use

of uniform quality assurance labels will be helpful in this.

18

Table I.2 Organic livestock production (number of animals) in Belgium (Source: Bioforum, www.bioforum.be)

Belgium Flanders Wallony

1999 2000 2001 2002 %/TLa 2001 2002 %/TL 2001 2002 %/TL

Cattle

Dairy cow 6713 7451 7285 8318 1.44% 1408 1355 0.42% 5877 6963 2.70%

Nursing cow 6713 7034 7262 7765 1.61% 247 172 0.10% 7015 7593 2.46%

Others 5031 10012 29930 26569 1.45% 1764 1649 0.17% 28166 24920 2.87%

Pigs

Sows 132 674 384 528 0.08% 234 229 0.04% 150 299 1.03%

Fattenig pigs 1906 9702 6131 4753 0.08% 1585 839 0.13% 4546 3914 1.27%

Others 5 23 8 15 0.01% 8 15 0.14% 4999 - -

Sheep 2919 7530 8116 8751 2.98% 3117 2843 3.06% 282 5908 11.07%

Goats 669 1552 1323 2076 8.30% 1041 1547 11.33% 168 529 4.66%

Horses 29 72 191 107 0.34% 23 13 0.06% 105 94 0.88%

Cervines 98 262 189 286 - 84 85 - - 201 -

Rabits 29 10 12 - 10 12 - 0 0 -

Poultry

Laying hens 21463 69327 68582 61104 0.43% 57264 39102 0.31% 11318 22002 1.74%

Table chicken 12422 49937 258395 36608 1.53% 50185 101744 0.49% 208210 264264 8.57%

Turkeys 6713 150 356 601 - 338 370 - 18 231 -

Snails - - - 40000 - - - - - 40000 -

Total 65099 163900 388162 526893 1.10% 117308 149975 0.26% 270854 376918 6.08%

Area 18515 20265 22410 24874 1.78 4026 3879 0.63% 18384 20995 2.78% a TL= Total Livestock

19

I.A.2. WELFARE, PERFORMANCE AND MEAT QUALITY OF FATTENING PIGS

IN ALTERNATIVE HOUSING AND MANAGEMENT SYSTEMS: A REVIEW

ABSTRACT

Conventional husbandry systems for pork production are scrutinized by members of the

general public as well as the scientific community. As a response, alternative forms of pig

production, like outdoor housing, organic farming and environmental enrichment are gaining

interest. The question poses itself whether these production systems are indeed able to

improve the welfare and health status of the animals, and whether these production systems

alter production characteristics and meat or carcass traits.

Indicators of poor welfare have been described, but evaluating overall welfare is difficult.

Certain parameters of alternative housing will improve welfare in some way, but

simultaneously, other welfare problems are emerging and the weighing of each of these

problems is quite subjective. Alternative housing systems allow pigs to display species-

specific behaviour and decrease the occurrence of abnormal behaviours by acting on several

parameters: indoor vs. outdoor housing, floor space/density, floor type, and provision of

bedding or other types of environmental enrichment. Evaluating alternative housing systems

should be performed considering all the welfare-improving factors and the cost of alleviating

welfare-affecting problems in a given production system.

Data on growth, meat and carcass traits in alternative production systems are inconsistent in

literature, indicating that other factors than the housing system may play an important role.

However, some alternative production systems that meet concerns of animal welfare scientists

and members of the general public can have an equal or even higher performance level in

conventional systems.

Keywords: Alternative housing, pig, welfare, growth, carcass quality, meat quality

After:

S. Millet, C.P.H. Moons, M.J. Van Oeckel and G.P.J. Janssens, 2004. Welfare,

performance and meat quality of fattening pigs in alternative housing and management

systems: a review. Journal of the Science of Food and Agriculture, accepted.

20

INTRODUCTION

Intensive pig farming has moved away from traditional methods applied in the past when pigs

were allowed to roam freely during the day and sleep in a spacious sty at night (reviewed in

Fraser (1984). Instead, pigs in recent decades are continuously confined to a limited, stimulus-

poor space for economical, ergonomical and health reasons, resulting in the production of

considerable quantities of high-quality carcasses.

Despite the good health status of the animals, both animal welfare scientists and many

members of the general public are concerned about the welfare of production animals in

conventional systems, even though their arguments are not based on the same scientific

grounds. Pigs confined in stalls are no longer able to express their full range of species-

specific behaviours or to be engaged in voluntary social interaction. Therefore, while food

safety and sensory quality are very important to consumers of pork, the quality of life of

production pigs has become a major point of concern as well.

Consumers nowadays are willing to pay extra for pork with certain assurances, including the

welfare of pigs being respected (Windhorst, 2001). Furthermore, the belief exists among

consumers that pork from animals raised in extensive systems is of better quality (Ngapo et

al., 2004a). Oude Ophuis (1994) showed that free-range labeling of pork resulted in a positive

connotation, but only for consumers that had prior experience with free-range pork, thus for

consumers that already had a positive attitude towards free-range pig production. Preferences

for meat from less intensive livestock production are driven by perception rather than intrinsic

product characteristics. As a result, over the past decades, alternative housing systems such as

outdoor housing, organic farming and application of environmental enrichment have gained

interest. Organic farming is the most regulated of alternative housing systems, thereby

imposing minimally on the environment and the welfare of production animals, and avoiding

the use of polluting agents, including antibiotics (Cabaret, 2003). The issue is whether these

new systems indeed improve welfare of farmed pigs and whether, given the fact that they

replace systems that already produce high-quality meat, they affect production characteristics

and meat or carcass traits. This review aims to evaluate the effects of alternative housing

systems on behaviour and health of fattening pigs and the subsequent differences in growth

performance, meat and carcass traits.

21

INDICATORS OF ANIMAL WELFARE

An encompassing definition of welfare is difficult to find as it is a man-made and complex

concept (Rushen, 2003). In the broadest sense “the welfare of an animal is its state as regards

its attempts to cope with its environment” (Broom, 1986). If the animal is unable to cope, it is

stressed (Broom, 1998). It is beyond the scope of this paper to elaborate on the concept of

stress and the problems associated with its use. Excellent overviews can be found elsewhere

(Barnett and Hemsworth, 1990; Broom, 1998; Moberg and Mench, 2000). Briefly, stress is

defined by Moberg (2000) as “the biological response elicited when an individual perceives a

threat to its homeostasis”. Depending on the situation, stress can be short-term (acute) or

long-term (chronic).

Housing is usually a long-term condition for farm animals (Rushen, 2003) and thus results in

a chronic state of an individual, be it stressed or not. Measures of poor animal welfare can be

summarized as: (1) increased mortality; (2) impaired growth and breeding ability; (3)

external/internal lesions and/or pain; (4) disease; (5) immunosuppression; (6) profound

physiological changes; (7) expression of few or no species-specific behaviours, and (8)

occurrence of behavioural abnormalities (Broom and Johnson, 1993). One type of behavioural

abnormalities are so-called stereotypies, which are repetitive invariant behaviours, apparently

without function (Ödberg, 1978). Stereotypies are often thought to develop as strategies to

cope with the limited stimuli available in captivity (Wechsler, 1995). In pigs, stereotypies

consist of bar biting, head-weaving, vacuum chewing, tail biting, rooting bare floor, and

maintaining dog sitting position in relation to apathy (Arellano et al., 1992; Bolhuis et al.,

2000; Fraser, 2003; Rushen, 2004).

Alternative housing systems generally improve welfare by providing the opportunity to

express species-specific behaviour and engage in interaction with conspecifics. However, by

doing so, these extensive systems might inflate other welfare problems, mainly related to

health (Gade, 2002). This trade-off makes it very difficult to evaluate overall welfare, also

because the value of each welfare problem is weighted differently by different scientists

(Fraser, 2003). Instead, Rushen (2003) advocates to evaluate specific problems within each

type of housing system. These problems can be identified using various parameters of a

husbandry system, which are discussed in the next section as well as their effect on pig

welfare and health. A good housing system with regard to animal welfare is one with a small

number of problems and/or with the possibility to improve upon the less positive conditions.

In conventional housing it is sometimes impossible to make appropriate changes such as

22

providing opportunities for greater locomotion in indoor pens with limited space, while it is

more straightforward to control parasites by a preventive deworming strategy in an alternative

housing system where animals are housed on pasture or on a paddock.

PARAMETERS OF ALTERNATIVE HOUSING AND THEIR EFFECT ON HEALTH

AND WELFARE

Table I.3 describes several housing systems that are discussed further on in this review. They

differ from conventional housing, mainly in the parameters discussed below.

Indoor vs. Outdoor

A major change from conventional to alternative housing systems is that pigs are kept outdoor

on paddocks or pasture. This allows for the animals to engage in extended locomotion

(Beattie et al., 1996; Johnson et al., 2001) and rooting (Beattie et al., 1996), the latter mainly

on pasture or if the outdoor paddocks are bedded with soil, straw or wood shavings. When

given the opportunity, pigs engage in a great amount of rooting behaviour, indicating this is a

part of their normal ethogram (Gomez et al., 2002). The effects of the presence of bedding are

presented below. The main health problem associated with outdoor housing in organic

farming is the occurrence of ecto- and endoparasites (Day et al., 2003). Hoffman et al. (2003)

noted mosquito bites and fleas in outdoor reared pigs. Also, housed outdoors, pigs are

exposed to sun and often sunburn arises in these conditions (Muirhead and Alexander, 1997).

On the other hand, Guy et al. (2002c) observed less adventitious bursitis, injuries, stomach

ulceration, lung damage, mortality and morbidity of disease in outdoor paddocks and straw

yards compared to pigs in fully slatted pens. Hansson et al. (2000) evaluated pig health by

studying the carcasses for tumours, abscesses, joint lesions, tail biting, lung lesions and finally

ascariosis and other liver diseases in a slaughterhouse survey. In the organic pigs, a

significantly lower percentage of animals showed abscesses, tail biting, pleuritis, and white

spots, whilst more arthritis and arthrosis was surveyed than in conventional pigs. However, as

it was a slaughterhouse survey, the results have to be considered very cautiously. The lower

percentage of white spots for instance can be explained by a lower incidence of ascariosis, but

an earlier infection, with already recovered lesions at the moment of slaughter is a possible

explanation as well. Vaarst et al. (1999) observed a wide variation in prevalence of disease in

Danish organic slaughter pig herds.

23

Hence, although some authors describe health problems in certain production systems, others

do not confirm this, indicating that with a good management, it might be possible to counter

such problems.

Floor space - density

When decreasing space allowance pigs made fewer and longer visits to an automated feeder

with higher feed intake, but showed depressed growth rate (Hyun et al., 1998a). They

remained in the feeder longer because they could escape from the crowded situation and

aggressive conspecifics. Ekkel et al. (1995) recorded lower coughing and sneezing

frequencies in a ‘Specific-Stress-Free’ (SSF) housing system, in which pigs were raised from

birth and were never mixed, in comparison with a conventional barn. Mixing of pigs after

weaning and at different stages in the production process is the cause of severe aggression

(Fraser, 1984; Friend et al., 1983), which results in lesions from scratches and bites. Fewer of

such lesions were observed in the SSF housing (Ekkel et al., 1995). Space allowance did not

seem to affect tail biting in commercial grower-finisher barns (Kritas and Morrison, 2004). If

mixing of pigs cannot be avoided, providing barriers in the pen will allow victims of

aggression to escape (Arey and Edwards, 1998). It is also possible to reduce potential

aggression by taking the individual aggressiveness into account and to mix only low-

aggressive animals (Erhard et al., 1997).

24

Table I.3 Different alternative housing conditions used for experiments

Outdoor (O)/ Indoor (I)

Number of pigs per pen Surface/ pig Bedding and enrichment

Beattie et al. (1995) I 6 2.3 m² (7-13 weeks)

4.7 m² (14-20 weeks) peat area and straw area

Beattie et al. (2000) I 8 1.75 m² (8-14 weeks)

3.5 m² (15-21 weeks) peat area and straw area

Beattie et al. (1996) I 6 0.5-2.3 m² peat area and straw area

Bridi et al. (1998) O 12 300 m² -

Day et al. (2002) I 10 1.12 m²

* 30cm chain * bucket chopped straw * commercial destructible enrichment device

de Jong et al. (2000) I 4 1.16 m² half concrete area covered

with straw

Ekkel et al. (1995)a I 10 0.7 m² -

Enfält et al. (1997) O 51 980 m² hut with straw bedding

Gandemer et al. (1990) O 8 50 m² 3 kg beets/day

Gentry et al. (2002a) O 40 2 m² hut with straw bedding

Gentry et al. (2002a) O 6 212 m² hut with straw bedding

Gentry et al. (2002a) I 25 <-

>1500 7.5 m²<->12 m² -

Gentry et al. (2002b) I 4 9.4 m² -

Geverink et al. (1999) I 4 1.16 m² half concrete area covered

with straw

Guy et al. (2002a; 2002b; 2002c) I 20 1.65 m² straw yards

Guy et al. (2002a; 2002b; 2002c) O 20 20 m² bedded hut

25

Hill et al. (1998) I 8 2 chains and 2 rubber devices

Hoffman et al. (2003) O 24 75 m² -

Klont et al. (2001) I 4 1.16 m² half concrete area covered with straw

Lambooij et al. (2004) I 10 0.7 m² straw bedding

Lambooij et al. (2004) I 30 1.25 m² -

Lebret et al. (2002) I/O 12 0.45/0.70 m² -

Lewis et al. (1989) I 2 20 m² -

Millet et al. (thesis)b I/O 4 2 m² indoor/2 m²

outdoor straw bedding

Olsson et al. (2003)b O 40 150 m² -

Pearce et al. (1989) I 8 0.72 m² chains, bar and rubber tires

Petersen et al. (1998b) I 40 0.9 m² -

van der Wal et al. (1993)c I/O 79 straw bedding

Warris et al. (1989) O 24 18.75 m² tree stumps, motor tyres

Wolter et al. (2001) I 25/50/100 0.68 m² -

a Specific stress free housing system: pigs that were not mixed and provided with straw b Organic farming c 'Scharrel' pigs

26

Floor type, bedding and enrichment objects

Pigs kept in substrate-impoverished conditions showed less diversity in behaviour in the home

pen as well as when they were faced with a behavioural challenge such as a novel object test

(Wemelsfelder et al., 2000). Providing bedding (mainly straw or soil) on solid or slatted

concrete floors makes these surfaces more comfortable to lie and walk on. A number of

studies indeed demonstrated that, when straw is provided as bedding, the activity of pigs

increases and the occurrence of abnormal behaviours is reduced (Arey, 1993; Beattie et al.,

1995; Beattie et al., 1996; Morgan et al., 1998; Petersen et al., 1995; Weber and Zárate,

2000). Also, the level of aggression between pigs in a straw-enriched pen has been shown to

decrease in comparison to pigs kept in barren environments (O'Connell and Beattie, 1999).

This is not to say that adding straw is positive on all accounts, especially in relation to

management and lameness. When pigs are kept on slatted floors, the mixing of straw with

manure can complicate the effective removal of manure using automated systems (Klont et

al., 2001). Whether they are solid concrete, concrete and partially slatted, or either of these

bedded with straw or soil, the type of floor will affect the prevalence foot lesions and

lameness (reviewed by Arey, 1993). Oftentimes, pigs housed on slatted floors show an

increased prevalence of heel erosions (Mouttotou et al., 1999). On the other hand, in the study

of Gentry et al. (2002a), pigs finished on wheat straw bedding showed a smaller number of

foot lesions, but the foot pad lesions were more severe than in the control group kept on

concrete-slatted flooring.

Straw is the main type of enrichment given to pigs. Relatively few other studies were done

testing other enrichment objects for pigs. Hill et al. (1998) found that, when providing pigs

with two chains and two rubber hoses, age has an effect on the time spent manipulating each

object. A clear preference developed for the hoses in the finishing stage, whereas after

weaning, interaction time with hoses and chains was similar. Animals seem to prefer soft,

pliable toys that are easy to manipulate. In a study by Apple & Craig (1992), four-week old

growing pigs played more with a rubber dog toy and a knotted rope than with a chain and a

hose. In the same study, a greater pen size resulted in less overall playing time. Other

enrichment objects used, mostly in combination with straw bedding, are pieces of forest bark,

tree branches (Wemelsfelder et al., 2000) and even car tyres (Edge et al., 2004). The latter

might be dangerous as car tyres contain metal wires which could potentially harm the animals.

27

EFFECTS OF ALTERNATIVE HOUSING AND MANAGEMENT ON GROWTH AND

CARCASS QUALITY CHARACTERISTICS (TABLE I.4)

Feed consumption, climate, space allowance, level of activity, live weight, genotype, health

status and stress can affect growth and carcass composition.

In environmentally enriched or outdoor housing systems, the level of activity is likely to be

increased, which suggests elevated energy requirements for maintenance.

Group housed pigs in an experiment of Petersen et al. (1998b) showed a slower daily gain and

a lower total fat content in comparison with individually housed pigs. This can be due to a

higher spontaneous activity, but a lower feed intake can also play a role since 40 pigs had to

share 4 feeders compared with the individual feeding and housing of the control group.

Similarly, de Haer et al. (1993) demonstrated a higher growth rate and backfat thickness in

individually housed pigs in comparison with pigs housed in pens of 8 animals, which could

partially be explained by a higher feed intake. In addition, several authors (Ferguson et al.,

2001; Gomez et al., 2000; Warnants et al., 2000) observed higher growth rates in individually

housed compared to conventionally housed pigs. Therefore, individual housing might not be

suitable to compare alternative and conventional housing. Training of pigs, housed

individually (Petersen et al., 1998b) and in groups (Enfält et al., 1993b; Petersen et al.,

1998b), did not affect daily gain or carcass lean meat percentage. Hale et al. (1986), on the

contrary, observed a faster growth in exercised pigs, without changes in carcass conformation.

Lewis et al. (1989) found no effect of exercise on daily gain of pigs, but the backfat thickness

of exercised pigs was lower.

In outdoor housing systems, maintenance energy requirements increase when the ambient

temperature is below the thermal comfort zone. Furthermore, allowing for increased activity

might also rise energy requirements. If outdoor housed pigs spend more energy for activity

and thermoregulation, consequently, with an equal feed consumption, a higher proportion of

the diet will be used for maintenance requirements. This results in a slower growth and a

lower fat content in the pigs at similar age. This hypothesis can only be confirmed in an

experiment based on restricted feeding, as feed intake is a major determinant in daily gain and

carcass quality. If the pigs can compensate the extra energy demands by eating more feed, the

growth rate can remain unaffected or rise (chapter III.A).

28

Table I.4 Influence of alternative housing on daily growth, backfat thickness and meat percentage

Author Type of housing Daily gain Backfat thickness Meat percentage

Ekkel et al. (1995) Specific-Stress-Free housing ↑

Gentry et al. (2002a) Pigs born and finished outdoors ↑ ↓ ↑

Gentry et al. (2002a) Deep bedding ↑ ↑

Lebret et al. (2002) Lower temperature indoors ↑ = =

Olsson et al. (2003) Organic pigs ↑ ↑ ↓

Beattie et al. (2000) Enriched housing ↑ from 55-100 kg ↑

Guy et al. (2002b) Outdoor paddocks // straw yards ↑//↑↑

straw yards higher than outdoor housed, fully slatted intermediate

Beattie et al. (1996) Enriched housing =

Bridi et al. (1998) Outdoor rearing = ↑ =

Enfält et al. (1993b) Effect of training = = =

Gentry et al. (2002a) Indoor-born pigs finished outdoors during winter = = =

Gentry et al. (2002b) Expanded space allowance = = =

Klont et al. (2001) Enriched housing = = =

Lewis et al. (1989) Exercise = ↓

Wolter et al. (2001) Groups of 50 and 100 pigs = = =

Enfält et al. (1997) Outdoor rearing ↓ ↓ ↑

Hale et al. (1986) Effect of training ↓ = =

Hoffman et al. (2003) Free range pigs ↓ ↓ ↑

Randolph et al. (1981) Crowded pigs ↓

Hyun et al. (1998a) Pigs with multiple stressors

↓ by crowingand mixing

Lebret et al. (2002) Outdoor rearing ↓ during summer ↓ during summer =

Petersen et al. (1998b) Effect of training & group housing in large pens

lower in group housed pigs

Lower total fat content in group housed

↓

Hill et al. (1998) Environmental enrichment/ isolation

treatment x genotypea

lower in isolated animals

higher in isolated animals

Gandemer et al. (1990) Outdoor housing ↓

29

Hansson et al. (2000) Slaughterhouse survey free range and organic pigs

↓

Lambooij et al. (2004) Straw bedding/free range housing =/=

van der Wal et al. (1993) Free range pigs trend to higher values ↓

Warris et al. (1989) Pigs in an outdoor paddock ↓b

a Commercial genotype pigs showed no differences in ADG by different forms of environmental enrichment, while pigs of an experimental genotype line supplied with toys showed higher ADG b In the group showing numerically the largest differences, the intensively reared pigs reached a higher live weight at slaughter than the extensively reared animals

However, a potentially reduced incidence of several kinds of stressors in alternative housing

systems will probably lower the energy requirements. In a study of Hyun et al. (1998a), space

reduction of pigs resulted in a lower daily gain without affecting feed intake. This effect was

attributed to increased energy expenditure as a result of increasing abnormal behaviour and

higher levels of aggression (Hicks et al., 1998). Randolph et al. (1981) noted a reduction in

daily gain and a higher feed to gain ratio in crowded pigs, whereas feed intake was not

affected. There was evidence that crowding increases aggressive behaviour, but a correlation

between aggressive behaviour and performance of the pigs was not demonstrated. Reducing

stress positively affects performance (Ekkel et al., 1995). Several stressors like high cycling

temperature, stocking density and regrouping depress the average daily feed intake and

subsequent daily gain (Hyun et al., 1998b). A positive linear relationship between on the one

hand space allowance and on the other hand daily feed intake and daily gain of group housed

pigs was found by NRC-89 (Arthur et al., 1993).

Lebret et al. (2002) showed the importance of temperature on daily feed intake and growth

rate, both in indoor and in outdoor housed pigs. They compared indoor housed pigs at either

17°C or 24°C with outdoor housed pigs in both winter and summer circumstances. Average

outdoor temperatures in summer and winter were respectively 26°C and 18.3°C, but with

large day to day variations. In comparison to indoor housed pigs at 24°C, the indoor housed

pigs at 17°C showed higher growth rates. Outdoor housed pigs during winter and summer

showed similar and lower growth rates respectively than indoor housed pigs at 24°C. The

indoor pigs at 17°C and the outdoor pigs in winter showed significantly higher feed intakes,

whilst the outdoor pigs during summer showed a trend to a lower feed intake. Cold stressed

pigs spent more time feeding in the experiments of Hicks et al. (1998), but this was not

accompanied by a higher feed intake.

30

The rate of fat accretion will depend on the amount of feed consumed and the maximal daily

rate of protein accretion. Van der Wal et al. (1993) and Hansson et al. (2000) found lower

lean meat percentages in respectively, free range and organically grown pigs than in

conventionally fattened pigs. Similarly, lower muscle percentages and higher fat thickness,

were found for outdoor housed pigs (Gandemer et al., 1990) and organically raised pigs

(Olsson et al., 2003). This was accompanied by a faster growth. Therefore, the maximal

capacity for protein deposition might be attained, with consequently extra fat deposition. Bridi

et al. (1998) detected a higher backfat thickness but equal meat percentage in outdoor reared

pigs and pigs in organic housing conditions respectively. On the contrary, Warris et al. (1983)

found a lower backfat thickness in outdoor versus indoor raised animals. In this experiment,

however, live weight at slaughter and treatment group was confounded. The intensively

reared pigs reached a higher live weight at slaughter than the extensively reared animals.

Therefore, both the housing system and the higher live weight may explain the higher fat

thickness. Subcutaneous fat thickness increases with carcass weight (Beattie et al., 1999).

Enfält et al. (1997) and Gentry et al. (2002a) noticed leaner carcasses in outdoor versus

indoor reared pigs. Probably because the feeding was not entirely ad libitum, the outdoor

fattened pigs in the experiments of Enfält et al. (1997) could not compensate for extra energy

demands, leading to a slower growth than the indoor housed pigs, which can explain the

leaner carcasses. In addition, in an experiment by Hoffman et al. (2003), lower feed intakes of

free range pigs led to slower growth rates and lower backfat thickness. Gentry et al. (2002a)

found a higher average daily gain for outdoor pigs during warm months compared with indoor

pigs, whereas in the winter months no differences were found between both groups. Guy et al.

(2002b) observed significantly higher backfat levels in pigs grown in straw yards compared

with outdoor pigs; pigs housed in a conventional barn showed an intermediate backfat level.

Klont et al. (2001) did not observe differences in meat percentage between pigs raised in

barren and enriched housing systems, nor did Gentry et al. (2002b) in pigs with increased

space allowance.

In addition, Enfält et al. (1997) detected an interaction between sire breed and rearing form

for the leanness in the ham. In the experiments of Hill et al. (1998), genotype and forms of

enrichments tended to interact, with similar average daily gain and feed to gain ratios in a

commercial pig genotype and improved average daily gain and feed to gain ratio’s in an

experimental line receiving toys in contrast to other types of enrichment. Thus, the choice of

the genotype in relation to the housing system can be important in view of production traits.

31

In conclusion, alternative production leads in a majority of studies to an equal or even a faster

growth. Several factors in alternative housing systems can lead to an increased appetite and

consequently a higher feed intake. In this case, the extra energy needs related to these systems

can be overcompensated, even resulting in a higher daily gain. In some studies this higher

growth rate is causing extra fat deposition, leading to lower muscle percentages. It is clear that

daily feed intake will be one of the determining factors for the obtained daily gain and

ultimate carcass quality, in combination with the factor genotype.

EFFECTS OF ALTERNATIVE HOUSING AND MANAGEMENT ON MEAT QUALITY

CHARACTERISTICS

Literature gives two explanations for potential housing effects on meat quality, being

differences in preslaughter stress and physical training. Animals in alternative housing

systems can engage in extended locomotion, since they often have more space allowance and

more stimuli to move. For this reason, the physical activity during loading and transport of

these animals might not be as demanding physically and might be less stressful. In the next

sections several factors of meat quality in relation to alternative housing systems and

management systems will be discussed: (1) muscle glycogen content, lactate and pH-values;

(2) meat colour and muscle fibre characteristics; (3) intramuscular fat content and (4) meat

tenderness, water holding capacity and juiciness of the meat.

Muscle glycogen content, lactate, and pH-values (table I.5)

Dark, firm and dry or DFD meat occurs in pigs that were exhausted at slaughter. The

exhausted pigs have muscles with a very low glycogen content, thus only minor amounts of

lactic acid can be formed. The pH decrease is somewhat lower than for normal meat, resulting

in an ultimate pH above 6.0. The incidence of DFD meat is rather limited in pig carcasses. It

can be expected that alternatively housed pigs, with more opportunity for exercise than

indoor-penned pigs, do not become as exhausted during loading, which could be positive in

relation to the incidence of DFD meat.

With increasing physical fitness, muscles generate relatively less ATP through anaerobic

pyruvate catabolism (Geor et al., 1999), which reduces muscle lactate formation. Lactate

formation following physical stress was significantly lower in trained versus untrained pigs

(Jorgensen and Hyldgaard-Jensen, 1975).

32

Higher liver glycogen levels are correlated with a lower ultimate pH (Warriss et al., 1989).

Glycogen content and ultimate pH are determined by many factors. Metabolic and contractile

properties of muscle are important sources of variation in glycogen content (Fernandez and

Tornberg, 1991). All the events occurring during the handling of pigs before slaughter can

lead to a depletion of muscle glycogen (Fernandez and Tornberg, 1991). Muscle glycogen

content at slaughter was higher in m. biceps femoris of moderately exercised than in non-

exercised crossbred pigs (Essén-Gustavsson et al., 1988). Enfält et al. (1997) noted more

glycogen in the muscles at slaughter and a significant lower ultimate pH in outdoor reared

pigs in comparison to conventional ones. The higher glycogen level before slaughtering

would implicate a lower risk for DFD meat, but a greater risk of being pale, soft and

exudative (PSE). PSE meat occurs more frequently in pig carcasses than DFD meat. PSE

mostly occurs in pig muscles with a high glycolytic potential. According to Enfält et al.

(1993a), the development of muscles with PSE characteristics is initiated by a combination of

a lower muscle pH at exsanguination, due to lactate accumulation before slaughter, and a

faster pH decrease post mortem, when the carcass temperature is still high. As early as 45 min

post mortem a pH of 5.6 - 5.8 is reached in PSE meat, but the ultimate pH is similar or

slightly lower than in normal meat. PSE meat is caused by severe, short-term stress just prior

to slaughter, which leads to a rapid breakdown of muscle glycogen. Alternatively housed pigs

seem to cope better with stressful circumstances at slaughter (see chapter III.B).

In contrast to free range pigs, Lambooij et al. (2004) observed higher lactate formation in

conventional pigs, resulting in a lower initial pH. Even so, Petersen et al. (1997) observed

lower pH values 45 minutes post mortem in female confined pigs in comparison with trained

pigs or group housed pigs. In both studies, ultimate pH was not affected by the treatments.

Neither did Lewis et al. (1989) find an effect of exercise on ultimate pH of m. longissimus

dorsi and m. quadriceps femoris. Similarly, Enfält et al. (1993b) observed no effect of

walking 735 m a day of the animals on glycogen content and ultimate muscle pH in m.

longissimus dorsi and m. biceps femoris.

33

Table I.5 Influence of different housing systems on meat pH at 45 minutes and 24 hours after slaughtering

Type of housing Initial pH Ultimate pH

Ekkel et al. (1995) Specific-Stress-Free housing ↓ ↑

Klont et al. (2001) Enriched housing = ↑

Beattie et al. (2000) Enriched housing ↓ =

Bridi et al. (1998) Outdoor rearing = =

Enfält et al. (1993b) Effect of training =

Gentry et al. (2002a) Indoor-born pigs finished outdoors during winter = =

Gentry et al. (2002a) Pigs born and finished outdoors =

Gentry et al. (2002b) Expanded space allowance ↑ =

Geverink et al. (1999) Enriched housing = =

Guy et al. (2002b) Outdoor paddocks // straw yards =

Hoffman et al. (2003) Free range pigs = =

Lambooij et al. (2004) Straw bedding ↑ in m biceps femoris =

Lebret et al. (2002) Lower temperature indoors = =

Lewis et al. (1989) Exercise = =

Petersen et al. (1997) Effect of training & group housing in large pens

lowest in trained, highest in group housed pigs, confined intermediate

=

Petersen et al. (1998b) Effect of training & group housing in large pens

higher in m. biceps femoris of sows. lower in trained versus group housed

=

van der Wal et al. (1993) Free range pigs = =

Warris et al. (1989) Pigs in an outdoor paddock = =

Hale et al. (1986) Effect of training ↓

Lambooij et al. (2004) Free range housing ↑ ↓

Olsson et al. (2003) Organic pigs interaction with genotype

Gandemer et al. (1990) Outdoor housing lower in m. adductor longus

Beattie et al. (1995) Enriched housing tended to be lower in outdoor paddocks

34

Different forms of environmental enrichment, or outdoor housing did not alter muscle

glycogen content (van der Wal et al., 1993; Warriss et al., 1989) or pH values (Gentry et al.,

2002a; Geverink et al., 1999; Hill et al., 1998; Hoffman et al., 2003; van der Wal et al., 1993).

Guy et al. (2002b) saw lower initial pH values for outdoor housed pigs although not

statistically significant. Klont et al. (2001) determined a higher ultimate muscle pH at 24

hours post mortem in pigs on a straw bedding.

In general, experimental housing conditions did not alter in a consistent manner initial or

ultimate pH, indicating that other factors are more determining for the glycolysis rate and the

resulting meat quality.

Genetics will be of major importance for meat quality. Breed together with pre-slaughter

handling are determining for the muscle glycogen content (Fernandez and Tornberg, 1991).

Warris et al. (1983) detected an interaction between breed and rearing environment for haem

pigment. In an experiment of Olsson et al. (2003), type of production interacted with the

presence of the Rendement Napole allele on ultimate pH, drip loss and shear force value.

Nutrition might affect meat quality as well. Rosenvold et al. (2001) demonstrated that by

feeding finishing pigs diets low in carbohydrates and high in protein 3 weeks prior to

slaughtering, the muscle glycogen stores at slaughter can be reduced. Hence, both genotype

and to a lesser extent nutrition will be important for meat quality.

Meat colour and muscle fibre characteristics

Meat colour is influenced by different factors like post mortem glycolysis rate, intramuscular

fat content, pigment level and oxidative status of the pigment (Lindahl et al., 2001; Van

Oeckel et al., 1999).

Conventional myofibre typing, based on differences in sensitivity of the acto-myosine-ATP-

ase activity to pH preincubation distinguished 3 fibre types in pig muscles, i.e. type I, IIa and

IIb. Type I are slow-twitch and type II are fast-twitch fibres. Type I fibres are oxidative,

whereas type IIa fibres are oxido-glycolytic, and type IIb fibres consist of oxido-glycolytic

and glycolytic fibres. A more appropriate typing, taking into account the presence of 4 adult

myosine heavy chains differentiates between fibre type I, IIa, IIx and IIb. Speed of contraction

increases from type I over type IIa and IIx to IIb (Lefaucheur, 2004). An increased proportion

of glycolytic fibres is associated with a decreased myoglobin content, which can result in

paler meat, while an enhanced oxidative metabolism leads to more red meat, but also a

reduced muscle colour stability (Henckel et al., 1997; Lefaucheur, 2004).

35

Physical training increases the oxidative capacity of skeletal muscles in different species

(Hodgeson and Rose, 1994; Jorgensen and Hyldgaard-Jensen, 1975; Marlin and Nankervis,

2002). However, Enfält et al. (1993b) could not demonstrate an effect of exercise on haem

pigment. In experiments of Petersen et al. (1998a), physical activity induced a change in

muscle fibre characteristics. The results differed between muscles types, type of training and

sex of the animals. A shift from IIb towards IIa-fibres was seen in m. semitendinosus and m.

biceps femoris of exercise trained male pigs or male pigs with allowance for spontaneous

activity in comparison with confined pigs. Both training and activity increased the proportion

of type I fibres in the M. trapezius thoracis, whereas no effect was seen in the m. longissimus

dorsi of trained pigs. In pigs housed in large pens, the ratio of IIa to IIb-fibres of m.

longissimus dorsi increased, but interactions between gender and physical activity were noted.

Exercise thus affects muscle fibre type in that in general, a shift occurs towards more

oxidative fibres, but the function of the muscles as well as the type of activity seems to

influence the distribution pattern.

Gentry et al. (2002b) found no differences in colour or fibre type distribution between

conventional pigs and pigs with increased space allowance, while Bridi et al. (1998) observed

more red meat in outdoor housed pigs. Warris et al. (1983) observed slightly paler meat in

intensively reared pigs than in pigs reared in an outdoor paddock. This effect could not be

attributed to a lower haem pigment or a lower pH1-value as these parameters were not

significantly affected. Gentry et al. (2002a) and van der Wal et al. (1993) found no effects of

housing on meat colour. Haem pigment was not different between confined, trained or group

housed pigs in the experiments by Petersen et al. (1997). They observed slightly higher

reflectance values in exercised than in control pigs. Enfält et al. (1997) also found a tendency

towards higher internal reflectance values in outdoor reared pigs.

In conclusion, housing type will predominantly affect meat colour by influencing the muscle

fibre type as a result of a training effect, although other factors may be of importance as well.

The type of housing and the space allowance may influence the level of activity and therefore

meat colour.

Intramuscular fat content

Several studies suggest a favourable relationship between intramuscular fat (IMF) content and

juiciness and tenderness of pork (Fernandez et al., 1999a; Hodgson et al., 1991). According to

Fernandez et al. (1999b), an increase in IMF level up to a level of 3.5% enhances the

consumer’s acceptability of pork.

36

Enfält et al. (1997) found a tendency towards lower IMF levels in outdoor reared pigs

compared to indoor housed pigs (2.3% vs 2.6%). Likewise, in 1993, they detected a lower

IMF level in exercised pigs (Enfält et al., 1993b). Others (Olsson et al., 2003) demonstrated

that organic housing led to a lower IMF level than conventionally housed pigs. No effect on

IMF level was seen in free range pigs (van der Wal et al., 1993), or pigs reared outdoor

(Lebret et al., 2002). However, other than housing and management, factors like nutrition will

also be important and might even overrule housing effects. For instance, in organic pig

husbandry, the absence of synthetic amino acids can lead to a higher IMF content (Sundrum

et al., 2000a).

Water holding capacity, juiciness and tenderness of meat

Enfält et al. (1997) and Olsson et al. (2003) found a lower water holding capacity for outdoor

or organically reared pigs compared with conventionally reared pigs, while water holding

capacity was unaffected by outdoor rearing in several studies (Lambooij et al., 2004; van der

Wal et al., 1993; Warriss et al., 1989). In addition, Gentry et al. (2002b) found no differences

in water holding capacity between conventional pigs and pigs with increased space allowance.

Juiciness of the m. biceps femoris of male pigs was positively affected by training of the pigs

in an experiment by Petersen et al. (1997)

The indoor reared pigs in a study by Enfält et al. (1997) showed lower shear force values and

greater meat tenderness and juiciness than outdoor reared pigs. Likewise, van der Wal et al.

(1993) found lower shear force values in the m. longissimus dorsi of indoor compared to

outdoor housed pigs.

In a study by Lewis et al. (1989), exercise of the pigs had a negative effect on the tenderness

scores by taste panel of the m. longissimus dorsi, but shear force values were not statistically

affected. Similarly, Petersen et al. (1997) and Essén-Gustavson et al. (1988) noted no effect of

training of pigs on shear force values of the m. longissimus dorsi.

In conclusion, water holding capacity remained unaffected or was lower in outdoor reared

pigs. Juiciness was positively affected by training in one experiment and outdoor housing led

in a few number of studies to decreased tenderness of the meat.

37

CONCLUSION

Several parameters can be changed in alternative housing systems compared to conventional

husbandry of fattening pigs. Most allow animals to display their species-specific behaviour

repertoire as well as engage in social contact. On the other hand, such changes might

endanger welfare of pigs in other areas, mostly related to health. Nonetheless, it is easier for

alternative housing systems to deal with such problems through good management than for

conventional husbandry to change in such a way that behavioural needs of pigs are met.

Alternative housing systems also affect pigs’ production characteristics. In several studies,

pigs in an alternative production system show an equal or in some cases a better performance,

which can lead in some, but not all, cases to lower meat percentages. Genetics will interfere

with this, as the maximal capacity of protein accretion will be determining for the fatness of

the animals. Meat quality characteristics will be influenced by housing and management

parameters, although unambiguous conclusions for the effects of one housing type on these

parameters cannot be drawn. Therefore, other factors like nutrition and genetics have to be

considered. Van Oeckel (1999) gave an overview of influencing factors on pork quality. Still,

these studies demonstrate that alternative production forms might lead to acceptable

production performance or meat quality characteristics when compared with conventional

systems. Taking into account that these production systems are developed to enhance animal

welfare and that the general public opposes less to them, the absence of negative effects on

production quality encourages favouring alternative housing systems.

38

39

I.B. AIMS AND OUTLINE OF THE THESIS

Organic livestock production comprises several aspects and is determined by specific

housing, nutritional and management rules. These rules may elicit differences in the applied

production method, the nutritional needs, and livestock performance. However, the scientific

evidence on these potential differences is rather limited at this moment.

The aims of the thesis were:

* To determine protein utilisation in an organic pig barn.

* To evaluate the effects of organic housing and nutrition

* on performance.

* on carcass and meat quality characteristics.

* on the immunocompetence of fattening pigs.

* To determine the nutritive value of organic corn cob mix (CCM) in an organic barn

and the effect of this CCM inclusion on performance, meat quality and

immunocompetence.

To meet these aims, 5 experiments were conducted, either in the organic barn or in a

comparison between an organic and a conventional barn.

The first experiment was conducted in the organic barn, to determine the protein requirements

in an organic pig fattening barn. Nine groups of 4 pigs were used, on 3 protein concentrations.

This study is described in chapter II.

In the second and third experiment, a comparison was made between organic and

conventional feeding in either an organic or a conventional barn. In the second experiment the

pigs from the organic barn originated from an organic production system and the pigs from

the conventional barn from a conventional production system. In the third experiment, an

other breed was used, with a similar way of rearing from birth until weaning. In both

experiments, in each housing system, half of the groups received a conventional diet and the

other half an organic diet. Growth performance, meat and carcass traits were monitored, as

described in chapter III.A.1. (second experiment) and III.A.2. (third experiment). To evaluate

if organic housing or nutrition affect immune status, the effects of housing and nutrition on

immunocompetence were determined in the third experiment, as described in chapter III.B.

40

At a further stage, two experiments were conducted to evaluate CCM as a feedstuff in an

organic feed matrix. Therefore, the nutritional value was determined in experiment 4, after

which the inclusion of CCM in a balanced feed was evaluated in experiment 5. The impact on

growth performance and product quality during both experiments is described in chapter

IV.A and the influence of CCM inclusion in a diet on immunocompetence is described in

chapter IV.B. In both experiments, 36 pigs were used, 9 groups of 4 pigs divided over three

treatment groups. Pigs were held and fed in the same way from birth until 40 kg of

bodyweight. The experiments were performed between 40-110 kg.

41

CHAPTER II. DIETARY PROTEIN IN ORGANIC PIG NUTRITION

In organic pig fattening, the need for qualitative protein sources is a major hurdle. Therefore,

even more than in conventional pig nutrition, it is important to limit excessive protein content

in feed formulation. As organically housed pigs have more space allowance and outdoor

space, their maintenance energy requirements might rise. Therefore, the energy requirements

might rise in comparison with conventionally housed pigs, without relevant elevation in

protein requirements. In this chapter, the lowered protein concentrations in an organic pig

fattening barn are considered.

42

43

DIETARY PROTEIN FOR AD LIBITUM FED ORGANIC FATTENING PIGS

ABSTRACT

The effect of three dietary protein levels on growth, meat, and carcass traits was studied in

organic pigs (fed a three-phase diet). Assuming lysine as the first limiting amino acid, feeds

were formulated to ileal digestible (ID) lysine content, with the ID lysine to crude protein

ratio set at a constant ratio of 4%. Feeds were formulated to an isocaloric rate (net energy:

weaner 9.4, grower 9.25 and finisher 9.1 MJ/kg), with a high (HP), a medium (MP) or a low

(LP) protein content ranging from 20% to 14%. ID lysine content with a 20% and 10% lower

ID lysine level in the LP and MP feed respectively compared to the HP feed. The nutrient

formulation of the HP feed was similar to commonly used nutrient levels in Belgian

conventional farming. The pigs were housed according to EC regulations on organic farming.

From 20 to 40 kg, the pigs showed a better feed conversion ratio with an increasing protein

concentration (r2= 0.84, P= 0.001). This effect disappeared throughout the second and third

phase. A significant effect of protein concentration on voluntary feed intake in the second

phase was noted (P= 0.018), which was explained by a compensation for the lower protein

concentration in the LP feed. Analysis of the carcasses showed a lower meat percentage with

lower protein concentration (P< 0.05), whereas influences on meat quality were limited. In

conclusion, during the first phase of growth, a higher protein concentration leads to better

performances, but from the second phase on (45 kg), a decrease in protein content,

corresponding with a 10 % decrease in dietary ID lysine level in comparison to that accepted

in conventional pig fattening may be used in organic fattening pig nutrition.

Keywords: Pigs, Organic, Lysine, Energy, Growth, Carcasses, Meat

After:

S. Millet, E. Ongenae, M. Hesta, M. Seynaeve, S. De Smet, G.P.J. Janssens. Dietary

protein for ad libitum fed organic pigs, submitted.

44

II.1. INTRODUCTION

In organic pig nutrition, the availability of organic ingredients is limited. Moreover, the use of

synthetic amino acids is banned. Therefore, difficulties may rise in composing a feed with a

well-balanced protein content. At this moment, a limited list of non-organic ingredients can be

used to formulate a well balanced feed, up to a maximum of 20%. However, in future

legislation only organic ingredients may be used. Therefore, the limited availability of organic

ingredients supplying essential amino acids creates the need to determine the lowest amino

acid levels that satisfy production and quality traits.

The main differences between organic and conventional housing systems are the higher space

allowance, bedding material and the environment without climate control. When pigs are

allowed more space, their activity level is likely to rise. Close and Poorman (1993) calculated

an additional energy expenditure of 1.67 kcal ME/kg bodyweight per km walked in growing

pigs. Besides, lowering the environmental temperature increases the energy requirements

(Noblet et al., 1985). The higher energy requirements for activity and thermoregulation in

organic pig housing, therefore, are most likely to increase maintenance energy requirements.

Hence, optimal dietary protein concentration – or more accurately: ileal digestible (ID) lysine

to net energy ratio in the diet – may differ from that in diets for conventional pig fattening.

This study aimed to consider lowered protein concentrations in organic fattening pig nutrition,

with regard to performance, meat and carcass traits.

II.2. MATERIAL AND METHODS

II.2.1. Animals and management

A group of 36 pigs was used for this experiment. Pigs were terminal crossbreeds of a paternal

line and a maternal 3-way crossbreed of Seghers Hybrid (currently Rattlerow Seghers). The

paternal line was a homozygous stress positive Piétrain based line. The sows 3-way cross was

based on homozygous stress resistant closed lines of Large White, Landrace and a synthetic

line. Hence, the pigs were all heterozygous stress resistant. Since the genotype of the maternal

and paternal lines were known, it was not necessary to test the experimental pigs for stress

resistance.

All pigs were kept in a conventional way until weaning (4 weeks of age), after which they

were moved to an organic barn. From weaning to the onset of the study, all pigs received the

45

same organic starter diet (9.5 MJ Net energy for pigs, NEv/ kg feed, 9 g ID lysine/ kg feed).

The study was started when the pigs reached the age of ten weeks.

The pigs were divided into 9 groups of 4 animals, two barrows and two gilts. Each group was

randomly allocated to one of three diets: one with a high (HP), a medium (MP), and a low

protein concentration (LP) respectively, therefore providing 3 replicate groups per diet.

Each group of 4 pigs had access to an outdoor area of 8 m² with a concrete floor and an indoor

area of 8 m² with straw bedding. The barn was naturally ventilated and straw was replaced

once a week. Housing was in accordance with the EC-regulations on organic production

(Council of the European Union, 1999). One self-feeder (four feeder holes) and one nipple

waterer were provided in each pen. Environmental temperature was recorded with electronic

devices every hour (Testostor, Testo Ltd., Almere, The Netherlands).

All pigs were dewormed at the beginning of the study (Ivomec®, Merck), and vaccinated

against Aujeszky’s disease at the start of the study and four weeks later.

II.2.2. Feed

A three-phase feeding was applied, with a switch to the second and third phase feed at an

average pen weight of about 40 kg and 70 kg, respectively. Four basic feeds (tables II.1 &

II.2) were mixed to obtain the 9 experimental diets. Within each phase, the feeds were

isocaloric (see table II.3 for net energy and ID lysine contents). Feeds were formulated to a

minimal ideal amino acid pattern. In this way no amino acids other than lysine would be

limiting at any stage. Mixing the HP and LP feed in equal quantities formed the MP diet.

Mixing the first and third phase diet in equal quantities made the second phase diet.

By consistently formulating ID lysine at 4% of crude protein concent, we opted for a constant

lysine to protein ratio rather than keeping the crude protein or the ID lysine level fixed.

Considering the ban on synthetic amino acids in organic nutrition, it seemed most reasonable

to adapt both the ID lysine level and crude protein content together at a fixed ratio. The

percentage of 4% was based on what was reasonable within least cost formulation.

The feed was formulated in accordance with the EC guidelines on organic production

(Council of the European Union, 1999).

Feeds were produced by Molens Dedobbeleer (Halle, Belgium) and were subject to proximate

analysis (AOAC, 1980) and amino acid analysis. Amino acids were determined by cation-

exchange chromatography (Llames and Fontaine, 1994).

46

Table II.1 Ingredients of the different basic feeds (%)

High Energy Low Energy

High Lysine Low Lysine High lysine Low Lysine

Organic wheat 28.0 20.0 26.0 20.0

Organic barley 20.2 20.0 15.0 10.0

Organic pea 15.0 15.0 19.7 16.5

Organic corn 1.0 21.7 10.5 29.9

Organic soybean 16.5 4.5 - -

Wheat shorts 7.5 7.0 10.5 13.5

Non-GMO soybean - - 6.0 1.0

Potato protein 2.5 3.8 2.5 2.6

Corn gluten 2.0 - 2.0 -

Organic alfalfa - - 2.0 3.0

Malt sprouts 1.0 - 2.5 -

Linseed 1.5 - - -

Mineral and vitamin premixa 1.3 1.4 1.0 1.0

Molasses 1.5 1.5 1.5 1.5

Calcium carbonate 0.46 0.59 0.53 0.52

Monocalcic phosphate 0.47 0.59 0.05 0.14

vitE/Se 0.05 0.05 0.15 -

Linseed cake 1.0 4.0 - 0.2

Salt - - 0.05 0.21 a Vit A: 1000 IU/g; Vit D3: 200 IU/g; Vit E: 4 mg/g; Vit K3: 0.22 mg/g; Vit B1: 0.16 mg/g; Vit B2: 0.38 mg/g; Vit PP: 2.4 mg/g; Vit B6: 0.23 mg/g; Folic acid: 0.08 mg/g; Vit B12: 0.0024 mg/g, Vit H: 0.008 mg/g; Fe2+ 1%, Cu2+ 0.08%, Mn: 0.7%; Co: 0.004%; Zn: 0.8%; I: 0.004%, Se: 0.0032%, Choline: 35 mg/g; Ca: 19.25%; Na: 8.9%, Mg: 1.1%; Endo-1,4-beta-xylanase F.C. 3.2.1.8. 0.8 IU/g

47

Table II.2 Calculated (analysed) nutrient contents of the basic feeds (g/kg)

a NEv’97= net energy for production in pigs according to the Dutch CVB system 1998 b DP= digestible phosphorus c ID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cysteine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan and ID LYS= ileal digestible lysine

II.2.3 Slaughtering

Pigs were slaughtered when their individual bodyweight reached between 110 and 115 kg.

Feed was withdrawn overnight before slaughtering. The pigs were transported to the nearby

abattoir (6 km) in small groups of maximum 4 animals in a small trailer. During the transport

and lairage time, pigs of different pens were mixed, thus interaction between unfamiliar

animals was possible with all transports. The average time between arrival in the abattoir and

the onset of slaughtering varied from 2.5 until 3.5 hours between slaughter days. Pigs were

slaughtered with 4 minutes intervals. Pigs were slaughtered at random, so that differences in

High Energy Low Energy

High Lysine Low Lysine High Lysine Low Lysine

Dry matter 868.1 (882.0) 868.2 (886.0) 866.3 (882.3) 864.4 (865.6)

Crude ash 50.5 (53.0) 48 (48.7) 44.8 (43.0) 44.4 (44.2)

Crude fibre 41.6 (75.4) 37.5 (63.6) 45.0 (65.6) 43.3 (64.1)

Crude protein 198.6 (205.6) 159.8 (183.3) 175.3 (176.1) 143.2 (142.8)

Ether-extract 51.4 (54.9) 38.5 (44) 33.4 (39.6) 28.4 (31.4)

NEv’97 (MJ)a 9.4 9.4 9.1 9.1

Ca 6.5 7.0 5.4 5.5

P 5.5 5.2 4.5 4.6

DPb 2.2 2.2 1.4 1.4

Lysine 10.2 (8.6) 8.2 (7.3) 8.7 (8.1) 7 (6.4)

Methionine 3.1 (2.8) 2.7 (2.5) 2.8 (2.6) 2.3 (2.4)

Met + Cys 6.6 (6.3) 5.6 (5.3) 5.9 (5.7) 5 (5.4)

Threonine 7.4 (6.9) 6.2 (5.7) 6.5 (6.2) 5.4 (5.6)

Tryptophan 2.3 (2.2) 1.9 (1.8) 1.9 (2.0) 1.6 (1.8)

ID LYSc 7.9 6.4 6.5 5.3

ID MET/ ID LYSc 0.32 0.34 0.33 0.35

ID MET+CYS / ID LYSc 0.64 0.67 0.67 0.70

ID THR/ ID LYSc 0.68 0.69 0.68 0.69

ID TRP/ ID LYSc 0.22 0.21 0.20 0.20

48

lairage time between groups are limited. Pigs were bled in the hanging position after electrical

stunning on the floor with manually served tongs. Mean time difference between the end of

the stunning phase and the moment of sticking was generally between 20 and 40 seconds.

Between 1.5 and 2 hours post mortem, carcasses were placed in a conventional chilling room,

where they remained until the following morning. The same persons performed slaughtering

over the different slaughter days.

Table II.3 Ileal digestible lysine to net energy ratio (L:E) of the experimental diets over the three phases of

growth

HP MP LP

NEv’97 (MJ)a 9.4 9.4 9.4

ID LYS (g/kg) 7.9 7.2 6.4

L:E (g/MJ) 0.84 0.76 0.68 First phase 18-42 kg

protein (g/kg) 206 194.5 183

NEv’97(MJ) 9.2 9.2 9.2

ID LYS (g/kg) 7.2 6.5 5.8

L:E (g/MJ) 0.78 0.71 0.63 Second phase 42-71 kg

protein (g/kg) 191 177 163

NEv’97 (MJ) 9.1 9.1 9.1

ID LYS (g/kg) 6.5 5.9 5.3

L:E (g/MJ) 0.72 0.65 0.58 Third phase 71-113 kg

protein (g:kg) 176 159.5 143 a NEv’97 = net energy for production in pigs according to the Dutch CVB system 1998

II.2.4. Measurements

II.2.4.1. Production traits

Pigs were weighed individually at the time of switching to the next feeding phase. The

average daily gain (ADG) was computed per feeding phase as the difference between the final

and initial weight of the pen divided by the number of pig-feeding days during that phase.

Average daily feed intake (ADFI) was computed as total feed consumed by the pen during a

feeding phase, divided by the number of pig-feeding-days during that phase. Feed conversion

49

ratio (FCR) was calculated by dividing the feed intake of the pen during a feeding phase by

the weight gain of that pen during the same phase.

II.2.4.2. Carcass composition and meat quality

At the slaughterhouse, live weight and warm carcass weight were recorded. Muscle thickness

and fat thickness were measured using a CGM-device (“Capteur Gras-Maigre”; Sydel,

Lorient Cedex, France) to obtain the carcass lean meat percentage. Ham angle was measured

using an SKGII device (Eurocontroll Breitsameter GmbH, Friedberg, Germany) as an

indicator of carcass conformation. In addition, carcass length was measured, as described in

chapter III.A.

At 40 min (pH1) and 1 day (pH2) post mortem, pH was measured in the loin around the 13th

thoracic vertebra (m. longissimus thoracis et lumborum) and in the ham (m.

semimembranosus) of both carcass sides. Conductivity (Pork Quality Meter, Tecpro GmbH,

Aichah, Germany) was measured at 1 day post mortem in the same anatomical locations.

A piece of the loin of the right side anterior to the last thoracic vertebra was removed and

sliced. On these slices, water holding capacity, drip losses, shear force values, CIELAB

colour values and intramuscular fat content were measured as described in chapter III.A.

The Ethical Committee of the Faculty of Veterinary Medicine at Ghent University approved

the experimental procedures.

II.2.5. Statistical analysis

Data were analysed using a General Linear Model (variance analysis, SPSS 11.0.1 for

Windows, SPSS Inc., Illinois, USA). For performance parameters, the model included the

fixed effect of nutrition, considering pen as experimental unit. For the carcass and meat

quality traits, the model included the fixed effects of nutrition and gender as well as their

interaction term and the covariate warm-carcass weight, considering the animal as the

experimental unit. If a significant effect of diet was observed, Scheffé’s post hoc test was

executed.

Average values are presented as (x ± s.d.) unless otherwise mentioned.

50

II.3. RESULTS

At the onset of the study, the pigs’ average body weight was 18 ± 2 kg. At the time diets were

changed to the second and third feeding phase, the pens had reached an average weight of 42

± 2 kg and 71 ± 2 kg respectively. Average live weight at slaughter was 113 ± 4 kg.

The outdoor temperature averaged 19.5°C, 16.2°C and 8.6°C during the first, second and third

phase respectively, whereas the average indoor temperature evolved from 22.6°C to 21°C and

14.3°C during the respective phases.

Production parameters are presented in table II.4. During the first phase, the LP diet led to a

poorer FCR compared to the MP and HP diets. Average daily gain tended to be highest in the

HP group. The FCR was negatively correlated with dietary protein concentration during this

first phase (r²= 0.84, P= 0.001) as is shown in figure II.1. Pigs fed the HP feed showed a

numerically (non significant) higher protein intake than the MP and LP fed pigs (figure II.2).

Table II.4 Influence of dietary protein concentration on growth and feed efficiency of organic pigs

HP MP LP SEM P

Average daily feed intake (g/d) 1453 1352 1472 34 0.345

Average daily gain (g/d) 646 581 571 15 0.074 First phase (18-42 kg)

Feed conversion ratio (g/g) 2.25a 2.37a 2.53b 0.04 0.004

Average daily feed intake (g/d) 2316ab 2228a 2500b 46 0.018

Average daily gain (g/d) 862 840 886 13 0.424 Second phase (42-71 kg)

Feed conversion ratio (g/g) 2.69 2.65 2.83 0.03 0.066

Average daily feed intake (g/d) 3077 3059 3279 59 0.267

Average daily gain (g/d) 912 912 998 24 0.256 Third phase (71-113 kg)

Feed conversion ratio(g/g) 3.39 3.36 3.28 0.04 0.635

Average daily feed intake (g/d) 2314 2219 2388 38 0.204

Average daily gain (g/d) 808 773 810 13 0.467 Total (18-113 kg)

Feed conversion ratio (g/g) 2.87 2.87 2.95 0.02 0.116 a,b: different indices indicate significant differences by Scheffé’s post hoc test

In the second phase, feed intake was significantly higher when fed the LP diet compared to

the MP diet, whereas intermediate on the HP diet. Daily protein intake was higher in the HP

51

feed than in the MP fed group, with the LP group intermediate. No significant differences in

average daily gain were seen between the treatment groups, though the feed utilisation

efficiency tended to be lowest with the LP feed.

Neither feed intake, FCR nor ADG differed significantly between the three diets during the

third phase, although, numerically, ADG and feed intake were highest in the LP group. The

daily protein intake was significantly higher in the HP compared to the LP fed group.

Meat characteristics were hardly influenced by diet type (table II.5).

Only initial pH in the ham differed between the groups (P= 0.010). With regard to carcass

characteristics, lean meat percentage was lower (P= 0.043) and fat thickness was higher (P=

0.018) in the LP pigs compared to the HP and MP pigs.

y = -0.0123x + 4.7671R² = 0.84P=0.001

2.152.202.252.302.352.402.452.502.552.602.65

180 185 190 195 200 205 210Dietary protein concentration (g/kg feed)

Feed

con

vers

ion

ratio

Figure II.1 Correlation between feed conversion ratio and dietary protein concentration during the first

feed phase (20-45 kg) of organic pigs

52

Table II.5 Meat and carcass quality parameters of pigs fed a high (HP), a medium (MP) or a low (LP)

protein concentration (n= 6 per group). Average live weight at slaughter was 113 ± 4 kg.

HP MP LP

Barrow Gilt Barrow Gilt Barrow Gilt SEM P-value

Carcass lean meat (%) 57.3 59.3 55.8 60.9 51.5 56.5 0.9 diet*,sex*

Muscle thickness (mm) 66.0 66.9 67.2 68.5 65 67.3 1.1

Fat thickness (mm) 16.7 15.0 18.4 13.9 22 17.7 0.7 diet*,sex***

Length first rib-pelvis (cm) 82.5 82.8 81.8 84.0 82.8 82.2 0.3

Ham angle (°) 36.2 34.2 36.8 30.4 32.5 33 0.7 sex*

pH1ham 5.96 6.12 6.45 6.33 6.06 6.11 0.05 diet*

pH2 ham 5.55 5.58 5.60 5.56 5.64 5.63 0.02

pH1 loin 5.89 5.97 5.94 5.91 5.99 6.04 0.03

pH2 loin 5.46 5.47 5.45 5.45 5.49 5.49 0.01

PQM ham (µS) 10.93 10.45 10.45 11.07 11.38 10.62 0.21

PQM loin (µS) 8.86 8.52 8.09 9.56 7.88 7.93 0.23

Drip losses (%) 7.7 7.1 7.5 9.9 7.1 10.0 0.4 sex†

Filter paper method (mg) 121 111 123 136 101 135 4

Cooking losses (%) 25.9 24.8 26 24.2 24.8 26.1 0.4

Shear force (N) 33 39.7 35.2 27.2 32.4 33.2 1.5

Intramuscular fat content (%) 1.45 1.47 1.71 1.43 1.42 1.55 0.05

CIE L* 58.5 55 57.4 58.3 55.4 59.1 0.7

CIE a* 7.93 8.21 8.16 7.6 7.58 7.71 0.17

CIE b* 16.71 16.26 16.55 16.49 16.66 17.22 0.16 † P<0.1; * P< 0.05; *** P< 0.001 for main effects by ANOVA. There were no significant gender x diet

interactions.

II.4. DISCUSSION

As Belgium has a moderate climate zone, the pigs did not experience extreme temperature

changes. Therefore, in more extreme climatic conditions, nutrient requirements may differ

from levels found in this study.

The average temperature during the first phase indicates that the temperature was within

thermal comfort zone in this phase of growth (18-20°C; NRC, 1998). Therefore, possible

extra maintenance requirements could not be attributed to energy needs for thermoregulation.

However, the climate in the organic barn still differed from a conventional barn as there was

no climate control, with therefore broader variations in temperature between and within days.

53

During the second phase of growth, the average temperature was fairly good, whereas the pigs

during the third phase of growth may have experienced cold stress during some periods,

which may change the energy requirements and therefore alter the protein requirements

relative to energy.

By formulating an organic diet without adding synthetic amino acids, a change in protein

content will automatically lead to a change in lysine content. In addition, by formulating

methionine, cystine, threonine and tryptophan to a minimal ideal amino acid pattern, lysine

will be the first limiting amino acid. Effects seen from feeding the lower crude protein feeds

can therefore be attributed to a change in ID lysine content.

II.4.1. Production parameters

In the organic housing, pigs showed great appetite. This corresponds with other observations

comparing an organic system with a conventional system (chapter III.A).

The correlation between dietary protein concentration and FCR during the first phase is in

agreement with Chiba et al. (1991), who demonstrated a beneficial effect of a high lysine to

digestible energy ratio on feed utilisation efficiency. In this phase of growth of the present

trial, dietary protein concentration was the limiting factor for growth, rather than the energy

level. As a linear relationship was obtained between dietary protein concentration and feed

conversion ratio in this phase of growth, no plateau point was reached at the highest protein

level. Thus, a higher protein content than the 20.6% might lead to even better zootechnical

performances.

From the second phase on, an adequate crude protein level was reached of 17.7 %. In the

second phase, the LP feed tended to decrease the feed utilisation efficiency, with no

differences between the MP and the HP feed, suggesting a deficit in the LP feed.

As no differences could be noted in FCR or in ADG between the three diets during the third

phase, 14.3% dietary crude protein concentration seemed not limiting for growth at that stage.

The difference in feed intake during the second phase was remarkable as the feeds were

formulated to an isocaloric rate. Moreover, as mixing the HP and the LP feed formed the MP

feed, it was likely that eventual differences between feeds would behave linearly. Data in

figure II.2 suggest that the drive for a daily intake of protein had a primary role in feed intake

regulation.

54

a

a

ab

ab

b b

bab

0

100

200

300

400

500

600

First phase Second phase Third phase Total

Phase of growth

Gra

m p

rote

in in

take

per

day

HPMPLP

Figure II.2 Daily intake of protein by organic pigs fed diets with high (HP), medium (MP) or low (LP)

protein concentrations.

a,b: different indices indicate significant differences by Scheffé’s post hoc test

P= 0.113, 0.013, 0.030, and 0.008 (ANOVA) for the first, second and third phase and the whole experiment

respectively

It is stated that an animal tends to eat to fulfil its energy requirements (Ellis and Augspuger,

2001). From the present data, it can be stated that the HP group ate to fulfil the energy

requirements for maintenance and for growth. The MP group ate about the same quantities to

fulfil the energy requirements, thus eating less protein a day. As this had no influence on

production traits, the surplus in daily intake of protein of the HP in comparison to the MP

group might be considered as a non-essential fraction. The LP group seemed to eat to fulfil

their protein requirement for growth and maintenance, thereby eating a surplus in energy.

The protein intake in the MP and the LP group may have been the minimal daily protein

amount.

The hypothesis of a compensatory feed intake is supported by Henry (1985), who stated that a

diet that was made slightly deficient in lysine causes an increase in feed intake per unit of

metabolic weight. Lovatto and Sauvant, using a meta-analysis (2002), also showed an

increased feed intake with a lower dietary lysine and protein concentration. Nevertheless, it is

remarkable that the animals ingested a considerably high amount of feed per day to fulfil their

protein requirement. It is clear that these effects will only be noted by ad libitum feeding.

55

II.4.2. Meat and carcass parameters

Although there was no difference in growth characteristics during the third phase between the

three feeds, carcass parameters showed an effect of dietary protein concentration on meat

percentage. This suggests a shift to lipid deposition instead of protein deposition. Several

authors (Friesen et al., 1994; Mcphee et al., 1991) demonstrated that increasing the dietary

lysine fed to high lean growth pigs, as used in this study, results in a shift in composition of

gain from lipid to protein. Therefore, it is more likely that dietary protein content influences

meat percentage rather than daily gain. The results of the present experiment accord to these

findings. They suggest nevertheless a plateau point in lean growth at the level of the MP-feed.

This corresponds with a ID lysine content in the third phase feed of 5.9 g/kg and total dietary

lysine content of 7.25 g/kg. Yen et al. (1986) found optimal total lysine levels of 7.0 and 8.7

g/kg for conventional barrows and gilts respectively. In the present experiment, no interaction

could be detected between gender and dietary protein level on carcass measurements, thus

suggesting that the MP feed was able to fulfil the requirements, in contrast to the LP-feed for

both barrows and gilts. The somewhat lower levels of satisfying dietary ID lysine content in

this experiment was lower in comparison with that of Yen et al. (1986). This supports the

hypothesis that energy needs for thermoregulation and activity in organic housing were

higher, with consequently a lower protein need than in conventional housing. However, the

total dietary lysine content is only an approximation of the ID lysine content of a diet, which

is a more precise parameter. Moreover, protein content has to be related to energy

concentration of the feed. Finally, as Yen et al. (1986) slaughtered the pigs at a weight of

about 90 kg, the ideal protein:enery ratio will be higher than for those with a 23 kg higher

slaughter weight.

Blanchard et al. (1999) demonstrated that the consumption of diets with low protein to energy

ratios results, besides a higher carcass fat level, in a higher intramuscular fat content.

Increasing the intramuscular fat content enhances the consumers’ acceptability of pork

(Fernandez et al., 1999b). Differences in intramuscular fat due to altered dietary protein

concentrations could not be demonstrated in the present experiment. Furthermore, diets did

not affect other meat characteristics either, meaning that dietary protein content in se had no

considerable influence on these parameters. The effect of the diet on initial pH in the ham was

not accompanied by significant effects on other pH measurements and might not be relevant.

Concluding, meat quality does not rely on the differences in dietary protein concentration

ratio as determined in this experiment.

56

II.5. CONCLUSION

During the first phase of growth, a higher dietary protein concentration leads to better

performance, but from the second phase on (45 kg) a 10% drop in dietary ID lysine level in

comparison with levels commonly used in conventional pig fattening may be used without

performance losses. This level can be applied without negative effects on meat or carcass

parameters.

57

CHAPTER III. ORGANIC VERSUS CONVENTIONAL NUTRITION IN AN

ORGANIC AND A CONVENTIONAL PIG FATTENING SYSTEM

58

59

III.A. PERFORMANCE, MEAT AND CARCASS TRAITS

Both organic housing and organic nutrition differ at several points from conventional housing

and nutrition. The question rises if this other type of nutrition affects production parameters.

Besides, due to the increased space allowance and climatic differences, the housing may

potentially affect production results as well.

This chapter combines two analogous experiments on the effects of organic housing and

nutrition on performance and product quality. Therefore, in each experiment, 64 pigs were

divided over 4 diet and housing combinations. In chapter III.A.1, the pigs of the organic

housing had the same genotype (Piétrain boar x [Belgian Landrace x Duroc] sow) as the pigs

for the conventional housing, but the way of rearing was different from birth on. The organic

pigs were born outside, were weaned at 7 weeks of age and did not receive an injection with

iron dextrane. They received an organic diet from birth until the onset of the experiment.

In the experiment described in chapter III.A.2, all pigs were reared in a conventional way

from birth until weaning (4 weeks of age) after which the pigs for the organic housing were

moved to the experimental organic barn. The genotype of the pigs was a stress resistant

terminal crossbreed of a paternal line and a maternal 3-way crossbreed of Seghers Hybrid

(currently Rattlerow Seghers). Major parameters concerning performance were daily feed

intake, daily growth, and feed conversion ratio. Product quality was evaluated by means of

specific carcass and meat quality traits.

60

61

III.A.1. EFFECTS OF ORGANIC VERSUS CONVENTIONAL HOUSING AND

NUTRITION FROM BIRTH UNTIL SLAUGHTERING IN A CROSS OF

TRADITIONAL PIG BREEDS

ABSTRACT

The effects of organic housing and nutrition on growth performance, meat and carcass quality

traits were studied in a 2 x 2 factorial trial with two ways of housing and two types of feed,

i.e. conventional housing and feeding practices in Belgium vs. housing and feeding according

to regulations for organic farming. In both housing types, thirty-two pigs were kept in eight

pens with four pigs per pen. One half of the groups received an organic diet, the other half a

conventional diet. Both feeds were isocaloric, neither of them contained antibiotic growth

promoters. Three-phase feeding was applied. The conventional feed led to a more rapid

growth (P<0.05) during the first phase, due to a better feed conversion rate (P<0.001). This

effect disappeared during the second and third phase. Throughout the experiment, the pigs in

organic housing showed a markedly higher feed intake (P<0.001). Clear interactions between

housing and nutrition could not be demonstrated. The pigs from the organic barn did not

differ in carcass lean meat percentage, although they had a higher muscle and backfat

thickness. Organic nutrition led to a higher intramuscular fat content (P<0.05), a lower

ultimate pH in ham and loin (P= 0.02 and <0.001 respectively) and redder meat (P= 0.013).

The pigs from the organic barn showed a lower ultimate pH in ham and loin (P= 0.066 and

0.015 respectively) and redder meat. It was concluded that organic pig fattening does not

necessarily affect growth performance negatively, but meat quality traits can be influenced by

both organic nutrition and housing type.

Keywords: Pigs, Organic Farming, Carcass and meat quality, Growth, Housing, Nutrition

After:

S. Millet, M. Hesta, M. Seynaeve, E. Ongenae, S. De Smet, J. Debraekeleer, G.P.J.

Janssens, 2004. Performance, meat and carcass traits of fattening pigs with organic

versus conventional housing and nutrition. Livestock Production Science 87, 109-119.

62

III.A.1.1. INTRODUCTION

Over the last years, interest in organic production has increased. With Council Regulation

1804/1999 (Council of the European Union, 1999), the EU has completed its legislation on

organic farming and livestock production. However, today only a small percentage of pigs are

organically produced in Europe; e.g. in Belgium only 0.03% of national livestock pigs were

produced in an organic way in 1999 (chapter I.A). Nevertheless, the organic sector is

growing.

Among others, like veterinary and management rules, major differences between organic and

conventional pig production are situated in housing and feeding measures. Under organic

farming conditions animals must have access to an outdoor area, and inside they should have

more space and a resting-place with straw. Major differences in feeding management include

the ban of the use of synthetic amino acids and antibiotics, and the obligation to use at least

80% organically produced ingredients. Here, the main hurdle is the difficulty in finding

protein sources with a well-balanced amino acid pattern. Moreover, when pigs can benefit

from an outdoor area, energy requirements for activity and thermoregulation will increase.

Hence, they may require a feed with a higher energy to amino acid ratio.

The present investigation was conceived as a semi-holistic comparison between an organic

and a conventional pig fattening unit, with emphasis on housing and nutrition, in order to

reveal differences and similarities in zootechnical performance, meat, and carcass traits.

III.A.1.2. MATERIAL AND METHODS

III.A.1.2.1. Animals and management

Sixty-four crossbred piglets (Piétrain boar x [Belgian Landrace x Duroc] sow) were used in

this experiment. Half of the piglets was grown and housed in a conventional barn (CH). The

other piglets were reared and housed according to the national legislation on organic farming

(OH). Both barns were divided into eight pens, each housing two gilts and two castrated male

pigs.

Each of the pens was assigned to one of two diets: a conventional (CF) and an organic feed

(OF), providing 4 replicates per diet- and housing combination.

To avoid confounding of barn effects with parasitic infections, all pigs were dewormed at the

beginning of the study by an Ivomec® injection. As in conventional production systems, the

63

CH-pigs were dewormed again after 2 months. All pigs were vaccinated against Aujeszky’s

disease at the start and after 3 weeks.

Diets were changed to the second and third phase feed when the average weight within a

group reached approximately 45 kg and 70 kg respectively. The animals were slaughtered at

an individual live weight of approximately 105 kg. Before slaughtering, feed was withdrawn

overnight.

Animals were slaughtered at similar live weight, and not at similar age, as slaughter and

transport procedures could be standardized and differences in carcass weight would have

overruled other effects on carcass conformation or meat quality.

Pigs were brought in the morning (between 7:00 am and 8:00 am) to the nearby abattoir of

Ghent University (distance approximately 6 km) in small groups with a maximum of 4

animals. They were all transported by the same person in a small trailer. During the transport

and lairage time, pigs of different pens were mixed, thus interaction between unfamiliar

animals was possible with all transports. The pigs were slaughtered over 8 days, with a

minimum of 4 and a maximum of 12 animals slaughtered per slaughter day.

The average time between arrival in the abattoir and the onset of slaughtering varied from 1 to

5 hours between slaughter days. Pigs were slaughtered with 4 minutes intervals, hence lairage

time varied less within than between slaughter days. Differences in lairage time between

groups were limited because pigs were slaughtered at random. Pigs were bled in the hanging

position after electrical stunning on the floor with manually served tongs (250V). Mean time

difference between the end of the stunning phase and the moment of sticking was generally

between 20 and 40 seconds. Between 1.5 and 2 hours post mortem, carcasses were placed in a

conventional chilling room (2-4°C, 91-92% relative humidity), where they remained until the

following morning. The same persons performed slaughtering over the different slaughter

days.

Because susceptibility to stress has a significant influence on meat and carcass quality (Fisher

et al., 2000), the number of n alleles was determined by a DNA test (Coppieters et al., 1992).

III.A.1.2.2. Housing

The CH pigs had an indoor area with a surface of 1 m² per animal whereas the OH pigs had

access to an indoor area of 2 m² and an outdoor area of 2 m².

The organic housing consisted of an outdoor area with a concrete floor and an indoor area

with straw bedding. The surface in the conventional pens consisted of 75% of a concrete floor

64

without straw bedding and of 25% of slats. The conventional barn had climate control,

whereas the organic barn only had natural ventilation.

Straw was replaced weekly. One self-feeder (four feeder holes) and one nipple waterer were

provided in each pen. Environmental temperature and relative air humidity were recorded

with electronic devices every hour (Testostor, Testo B.V., Almere, The Netherlands).

III.A.1.2.3. Feed

The organic feed was formulated in accordance with the EC-guidelines on organic farming

(Council of the European Union, 1999). Ninety percent of feed ingredients were produced

following the regulations on organic farming, exceeding the minimum norm of 80% required

by national legislation. Hence, the organic feed formulation anticipated expected future

legislation.

The formulation and analyses of the feeds are presented in tables III.1 and III.2. A three-phase

feeding was applied. Within each phase, organic and conventional feeds were isocaloric.

None of the feeds contained growth-promoting antibiotics.

Because of the hypothesized lower requirement of digestible lysine per unit of energy, the

first and second phase organic feed was formulated at a 15% lower digestible lysine compared

to the conventional feed. As it was difficult to reach an ileal digestible lysine level as low as

5.6% in the last phase due to the limited choice of organic ingredients, the third phase organic

feed was formulated to a ten percent lower digestible lysine content compared to the

conventional feed. Feeds were produced by Molens Dedobbeleer (Halle, Belgium) and were

subject to proximate analysis and amino acid analysis. Amino acids were determined by

cation-exchange chromatography (Ooghe, 1983).

65

Table III.1 Ingredient composition (%)a of the experimental diets for pigs

Organic diet Conventional diet

Ingredient 20-45 kg 45-70 kg 70-105 kg 20-45 kg 45-70 kg 70-105 kg

Organic wheat 26 20.5 20 - - -

Organic barley 20 15 19.8 - - -

Organic pea 15 20 16.5 - - -

Organic corn 10.5 18 18.5 - - -

Organic soybean 8.5 1 - - - -

Wheat shorts 7.5 11.5 11.5 12 11 10.5

Non-GMO soybean 4.5 5 2 - - -

Potato protein 3 2.5 3.25 - - -

Corn gluten 1.5 1.5 - - -

Organic alphalpha - 2 2 - - -

Malt sprouts - - 4.5 - - -

Wheat - - - 49.7 50.5 50.3

Soybean - - - 24.5 18.5 15.5

Corn - - - 8.5 2.5

Barley - - - - 11.5 10

Beat pulp - - - - - 5

Alphalpha - - - - - 2

Soya oil - - - 2 - -

Wheat middlings - - - - 5 -

Mineral and vitamin premix 1.3 1.3 1 1.5 1.5 1.2

Molasses 1 1 0.5 - 1

Calcium carbonate 0.7 0.6 0.6 0.8 1 0.5

Monocalcic phosphate 0.5 0.3 0.1 - - -

VitE/Se 0.1 0.2 0.2 0.1 0.1 0.1

L-lysine - - - 0.16 - 0.11

DL-methionine - - - 0.05 0.04 0.02

L-threonine - - - 0.05 0.03 0.03

Cu-sulphate - - - 0.06 - -

Phytase - - - 0.09 - -

Fat - - - - 1.0 1.0

NaCl - - 0.15 - - 0.20 a If not specified, conventional ingredients were used

66

Table III.2 Formulated (analysed) nutrient composition (g/kg) of the experimental diets (as-fed basis)

First phase (20 to 45 kg) Second phase (45 to 70 kg) Third phase (70 to 105 kg)

Nutrient Organic Conventional Organic Conventional Organic Conventional

Dry matter 867 (888) 861 (899) 866 (840) 861 (858) 869 (876) 860 (880)

Crude ash 49 (48) 53 (53) 45 (43) 51 (54) 45 (44) 51 (79)

Crude fibre 37(47) 38 (50) 43 (55) 40 (48) 46 (62) 48 (50)

Crude protein 183(167) 186 (197) 169(168) 175 (176) 160 (160) 159 (170)

Ether-extract 43(37) 43 (33) 35(27) 34 (24) 28 (32) 32 (30)

NEv’97aMJ 9.46 9.4 9.2 9.1 8.98 9.08

Ca 7(7.7) 6.5 (8.9) 6(8) 6.8 (12.3) 5.5 (6.6) 5.5 (29.2)

P 5.3 5 5 5 4.6 4.5

DPb 2.1 2.2 1.8 1.9 1.4 1.8

Lysine 9.4 (9.3) 10.2 (10.7) 8.5 (8.2) 9.1 (9.8) 8.1 (8.1) 8.1 (8)

Methionine 2.9 (2.7) 3.2 (3.7) 2.7 (2.4) 3 (3.1) 2.6 (2.3) 2.6 (2.7)

Met + Cys 6.2 (5.1) 6.5 (6.8) 5.7 (4.3) 6.2 (5.8) 5.5 (4.2) 5.5 (4.9)

Threonine 6.9 (7.3) 7 (7.5) 6.3 (6.2) 6.4 (7) 6 (6.2) 5.8 (5.8)

Tryptophan 2.1 2.3 1.8 2.2 1.8 2

ID LYSc 7.4 8.6 6.5 7.6 5.8 6.5

ID MET/ID LYSc 0.32 0.33 0.33 0.34 0.33 0.33

ID MET+CYS /ID LYSc 0.65 0.64 0.6 0.67 0.6 0.68

ID THR/ID LYSc 0.68 0.63 0.68 0.63 0.68 0.65

ID TRP/ ID LYSc 0.21 0.22 0.2 0.23 0.21 0.24 a NEv’97 = net energy for production in pigs according to the Dutch CVB system 1998 b DP= ileal digestible phosphorus c ID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cystine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan and ID LYS= ileal digestible lysine

III.A.1.2.4. Measurements

III.A.1.2.4.1.Production characteristics

Pigs were weighed individually every three weeks and at changing of the feed phases. At that

time, feed consumption per pen was measured. Before weighing, feed was withdrawn

overnight.

Average daily feed intake was computed as total feed consumed by the pen during a phase

divided by the sum of the days the animals of the group that were present during that phase.

Average daily gain was computed per period as the difference between starting and final

67

weight of the animals of the pen divided by the days they were present during that period.

Feed conversion ratio during a period was calculated by dividing the feed intake of a pen

through the weight gain of the animals of the pen during that period.

III.A.1.2.4.2. Carcass composition and meat quality

In the abattoir, live weight and warm carcass weight were recorded. Muscle thickness and fat

thickness were measured using a CGM-device (“Capteur Gras-Maigre”; Sydel, Lorient

Cedex, France) in order to obtain the meat percentage. This instrument measures the

reflection at 850 nm by means of fibre optics, while traversing the meat. The European

Council accepted it as objective classification apparatus to measure lean meat content in pig

carcasses in the Belgian export slaughterhouses (Council of the European Union, 1997). In

addition, subcutaneous fat thickness was measured manually at the height of the first, seventh,

and last rib. The average of these measurements was further used. Carcass length was

measured as the distance between the bottom of the pubic bone and the bottom of the first rib

at the middle. Ham angle was measured using an SKGII device (Eurocontroll Breitsameter

GmbH, Friedberg, Germany) as an indicator of carcass conformation.

At 40 min post mortem (pH1) and 24 h post mortem (pH2), the pH was measured in the loin

around the 13th thoracic vertebra (m. longissimus thoracis et lumborum) and in the ham (m.

semimembranosus) of both carcass sides. Conductivity (Pork Quality Meter, Tecpro GmbH,

Aichach, Germany) was measured before cutting in the same anatomical locations.

The average of the measurements on both carcass sides for each animal was further used.

A piece of the loin of the right side anterior to the last thoracic vertebra was removed and

sliced. One slice was used for colour measurements by using the six-point Japanese pork

colour scale (1= PSE, 6= DFD) (Nakai et al., 1975) and by determining the CIELAB colour

co-ordinates in quadruplicate with a HunterLab Miniscan device after a 30 min blooming time

(D65 light source, 10° standard observer, 45°/0° geometry, 1 inch light surface, white

standard; Hunter, Reston, USA). These values are CIE L* (lightness), CIE a* (redness), and

CIE b*(yellowness). On this slide, water-holding capacity was measured with the filter paper

method as described by Kauffman et al. (1986).

A second slice was used to assess drip losses as the proportionate weight loss after hanging

the meat sample in a plastic bag for 48° at 2°C (Honikel, 1987).

Tenderness was evaluated by shear force determination after heating a third slice at 75°C for

60 min and cooling in tap water. On this slice, weight loss during cooking was regarded as

cooking losses. Shear force of the cooked samples was determined on cylindrical cores

68

(diameter 1.27 cm) taken parallel and sheared perpendicular to the fibre direction using a

Lloyd TA500 Texture Analyzer (Analis, Namur, Belgium) equipped with a triangular Warner

Bratzler shear force measurement device. (1 mm thickness, 60° angle, speed 200 mm/min).

Eight measurements per sample were recorded. Samples for shear force determination were

stored at –18°C prior to analysis.

A fourth slice was used to determine the content of intramuscular fat by means of the Soxhlet

method (ISO, 1973).

III.A.1.2.4.3. Digestibility

To determine the apparent digestibility of the two kinds of feed and to get an idea of the

bedding intake, 1.5% celite 545 was mixed in the first 150 kg of feed of the third phase (± 70

kg) as a source of acid insoluble ash (Furuya et al., 2001). Then, after an adaptation period of

one week, mixed fecal samples were taken for three consecutive days.

The apparent digestibility of the different components was computed during the third phase

by following equation:

ADX= 100*[1- (CD * XF)/(CF *XD)]

where ADX = apparent digestibility of component X (%)

CD= dietary concentration of celite

CF= fecal concentration of celite

XD= dietary concentration of component X

XF= fecal concentration of component X.

The Ethical Committee of the Faculty of Veterinary Medicine at the Ghent University

approved the experimental procedures.

III.A.1.2.5. Statistical analysis

Data were analysed using variance analysis. For performance parameters, the model included

the fixed effects of housing, nutrition and the interaction term housing x nutrition, considering

the pen as experimental unit. For the carcass and meat quality traits, the model included the

fixed effects of housing, sex, nutrition, their interaction terms and the covariate warm carcass

weight, considering the pig as the experimental unit. Japanese colour scale scores were not

normally distributed and were hence subjected to the non-parametric Kruskall-Wallis test

69

(Petrie and Watson, 1999). Average values will be presented as (x ± s.d.) unless otherwise

mentioned.

III.A.1.3. RESULTS

The average temperature in the organic barn increased from 11.2°C during the first phase to

14.6°C and 19.0°C during the second and third phase respectively. The corresponding average

outdoor temperatures were 7.0, 7.0 and 14.5°C. The temperature in the conventional barn was

on average 20.8, 21.1 and 22.7°C during the first, second and third phase respectively.

Variation in initial body weight was rather high (21 ± 6 kg). When the groups were changed

to second and third phase, the average weight within a group reached 44 ± 1 kg and 70 ± 3 kg

respectively.

III.A.1.3.1. Production characteristics

In the organic barn, one barrow on the organic diet broke a leg in the first week and was

replaced by a sow of approximately the same weight. In the conventional barn around the

switch from first to second phase feeding, two pigs, one of either type of diet, were removed

because of locomotory problems. During the second phase, one pig in the conventional barn

on the conventional diet, died because of an Actinobacillus pleuropneumoniae (App)

infection. After diagnosis of App in this pig, all other pigs of the conventional barn were

treated with antibiotics.

The effects of nutrition and housing on growth characteristics are summarized in table III.3.

During the first phase, the pigs on the conventional diet showed a lower FCR and higher

ADG compared to these eating an organic diet, whereas the opposite was seen during the third

phase. During the second phase, pigs fed the organic diet had higher ADFI and ADG than

those fed the conventional diet. During the whole study, a higher ADFI and ADG was seen in

pigs in the organic barn than those in the conventional barn.

A significantly higher FCR in conventional versus organic housing was only seen during the

second phase. Housing and nutrition did not interact for ADFI or ADG.

III.A.1.3.2. Carcass composition and meat quality

Most of the slaughtered animals were not stress susceptible, but carrier of one n-allel. In each

group, 1 or 2 homozygous stress susceptible pigs were detected: organic housing, organic

nutrition: 14 Nn, 1 nn; organic housing, conventional nutrition: 14 Nn, 2 nn; conventional

70

housing, organic nutrition: 3 NN, 9 Nn, 2 nn and conventional housing, conventional

nutrition: 3 NN, 10 Nn, 2 nn. As we are aware of the possible bias by the unequal number of

n-alleles in the treatment groups, statistical analyses for meat and carcass traits were first

performed on both a restricted dataset (with only the heterozygous pigs) and the whole

dataset. No substantial differences were found between the use of the restricted or complete

dataset. Therefore, statistics on the whole dataset are presented. Table III.4 gives meat and

carcass characteristics in function of nutrition and housing type. Significant effects of

nutrition or housing on lean meat content did not occur. Nevertheless, a higher muscle and fat

thickness was seen in pigs grown in the organic barn than those out of the conventional barn.

Intramuscular fat content was higher in the pigs given the organic feed in comparison to these

given the conventional feed. It was lower in the organic than in the conventional barn. Pigs

from the organic barn showed a shorter carcass length and a smaller ham angle, especially

within the organic feed groups. No effects of housing or nutrition were seen on conductivity

(PQM). Water-holding capacity as assessed by the filter paper method was similar, whereas a

trend towards higher drip losses on the conventional feed was found.

Housing type and nutrition influenced meat colour (tables III.4 and III.5). Pigs from the

organic barn had a higher redness score (CIE a*-coordinate). The CIE L* coordinate revealed

an interaction between nutrition and housing. Pigs on organic feed in organic housing had the

darkest meat, whereas pigs on conventional feed in organic housing had the palest meat. The

CIE b*-coordinate was significantly higher in meat from pigs in the organic housing

compared to those in the conventional housing. The Japanese colour scale indicated

significantly darker meat due to organic housing and due to organic nutrition.

The gilts had a higher lean meat percentage (P= 0.001), with an equal meat thickness but

lower fat thickness than the castrated male pigs (P<0.001).

An interaction of sex and housing was noted on redness score (P<0.043) and a trend to a

similar interaction on ham angle (P= 0.058). The gilts in the organic barn showed the reddest

meat, whereas the gilts in the conventional barn demonstrated the lowest redness score, the

barrows showing no difference in redness between the two barns. Even so, the gilts of the

organic housing showed a smaller ham angle than those of the conventional housing, the

barrows showing no significant differences.

71

Table III.3 Effect of nutrition and housing on technical performance of organically (OH) versus conventionally (CH) housed pigs, eating either an organic (OF) or a

conventional (CF) diet.

OH CH P-values

OF (n= 4) CF (n= 4) OF (n= 4) CF (n= 4) SEM Housing Nutrition Housing x Nutrition

Average daily feed intake (g/d) 1606 1619 1459 1409 35 <0.05 NS NS

Average daily gain (g/d) 643 722 583 634 17 <0.05 <0.05 NS First phase 21-43 kg

Feed conversion ratio (g/g) 2.50 2.24 2.50 2.22 0.04 NS <0.001 NS

Average daily feed intake (g/d) 2400 2355 2270 2002 48 <0.01 <0.05 <0.1

Average daily gain (g/d) 833 795 720 644 22 < 0.001 <0.05 NS Second phase 43-70 kg

Feed conversion ratio (g/g) 2.88 2.97 3.16 3.11 0.05 <0.05 NS NS

Average daily feed intake (g/d) 2938 2940 2575 2553 52 <0.001 NS NS

Average daily gain (g/d) 792 724 660 636 18 <0.001 <0.05 NS Third phase 70-105 kg

Feed conversion ratio (g/g) 3.71 4.07 3.91 4.02 0.05 NS <0.05 NS

Average daily feed intake (g/d) 2390 2403 2106 2033 49 <0.001 NS NS

Average daily gain (g/d) 760 741 647 636 16 <0.001 NS NS Total 21-105 kg

Feed conversion ratio (g/g) 3.15 3.24 3.25 3.20 0.03 NS NS NS

72

Table III.4 Effect of organic versus conventional feed and housing on meat and carcass characteristics of organic (OH) versus conventionally (CH) housed pigs,

eating either an organic (OF) or a conventional (CF) diet (n= 61a).

OH CH P-values OF (n= 16) CF (n= 16) OF (n= 14) CF (n= 15) SEM Housing Nutrition Housing x Nutrition Lean meat percentage (%) 56.6 56.3 54.9 56.9 0.6 NS NS NS Muscle thickness (mm) 61.4 59.5 55.7 56.2 0.8 <0.01 NS NS Fat thickness (CGM)b (mm) 16.4 16.3 16.8 14.9 0.5 NS NS NS Fat thickness (manual)c (mm) 32.6 32.1 28.7 27.5 0.7 <0.001 NS NS Distance first rib-pubic bone (cm) 82.19 81.25 82.93 82.87 0.28 <0.001 NS NS Ham angle (°) 35.9 37.9 42.2 39.4 0.7 <0.01 NS <0.1 pH1 ham 6.27 6.11 6.15 6.22 0.03 NS NS <0.05 pH2 ham 5.63 5.53 5.65 5.63 0.02 <0.1 <0.05 NS pH1 loin 5.85 5.80 5.92 5.95 0.02 <0.01 NS NS

pH2 loin 5.49 5.42 5.52 5.48 0.01 <0.05 <0.001 NS PQMd ham (µS) 9.1 9.8 9.6 9.7 0.2 NS NS NS PQMd loin (µS) 8.3 8.8 8.3 8.1 0.2 NS NS NS

Drip losses (%) 7.2 8.5 7.2 7.5 0.2 NS <0.1 NS

Water uptake filter paper method (mg) 98 106 101 95 3 NS NS NS

Cooking losses (%) 26.35 26.78 26.04 26.2 0.23 NS NS NS

Shear force (N) 36.8 33.4 38.2 38.2 0.9 NS NS NS

Intramuscular fat content (%) 1.37 1.19 1.61 1.39 0.06 <0.05 <0.05 NS

CIE L*e 55.6 60.1 57.6 58.3 0.5 NS 0.005 <0.05 CIE a*e 8.24 7.41 6.96 6.70 0.13 <0.001 <0.05 NS

CIE b*e 16.39 16.70 15.92 16.11 0.11 <0.05 NS NS a n= 60 for meat percentage and meat thickness, n= 59 for pH2 loin, n= 45 for PQM ham and n= 47 for PQM loin b Fat thickness measured with a CGM-device c Mean value of the subcutaneous fat thickness that was measured manually at the height of the first, seventh and last rib dConductivity measured with a Pork Quality Meter (Tecpro GmbH, Aichach, Germany) e CIE L* (lightness), CIE a* (redness), and CIE b*(yellowness): CIELAB colour co-ordinates measured in quadruplicate with a HunterLab Miniscan device after a 30 min blooming time (D65 light source, 10° standard observer, 45°/0° geometry, 1 inch light surface, white standard; Hunter, Reston, USA).

73

Table III.5 Interpretation of colour differences as influenced by housing and nutrition by use of

the Japanese colour scale

Housing Nutrition n mean rank P

Organic Organic 16 46.97

Conventional 16 27.81

Conventional Organic 14 25.54

Conventional 15 22.47

<0.001

III.A.1.3.3. Digestibility

Results are presented in table III.6. Effects of housing on apparent digestibility did not

occur. Apparent digestibilities of crude ash and crude protein were higher in the

conventional than in the organic diet during the third phase. A high standard deviation

was seen on digestibility of crude ash and crude fibre.

Table III.6 Apparent nutrient digestibility in the organic and the conventional third phase

feed (%)

Nutrient Organic Feed Conventional Feed P

Crude ash 2 ± 5 19 ± 9 0.001

Crude protein 76.2 ± 1.8 79.0 ± 2.5 0.021

Ether-extract 62 ± 6 63 ± 6 NS

Crude fibre 19 ± 16 11 ± 28 NS

N-free extract 89.6 ± 2.4 91.6 ± 2.4 NS

74

III.A.1.4. DISCUSSION

Enfält et al. (1997) stated that organically grown pigs and pigs with outdoor

allowance reached slaughter weight at a later time in comparison to conventional

housed pigs. In contrast to that study, where the pigs received restricted feeding, pigs

in the present study were fed ad libitum. The pigs housed according to organic

principles had higher feed intakes during the whole fattening period, leading to higher

growth rates at a similar FCR, compared to the conventionally housed pigs.

The fact that during the second phase (45-75 kg) feed conversion was higher in the

conventional barn than in the organic barn can probably be attributed to a subclinical

Actinobacillus pleuropneumoniae infection, as one of the animals died due to this

pathogen.

It is surprising that the FCR in the organic barn was not higher than in the

conventional barn, since it was hypothesized that higher activity and increased energy

requirements for thermoregulation would increase the proportion of energy

requirements for maintenance. Because feed intake and growth rate were both higher

in the organically housed animals, the pigs spent higher daily energy to growth. Thus,

the energy expenditure was not only increased for maintenance, but also for growth.

Hence, the ratio between energy demands for maintenance and growth were similar to

that in the conventional barn, which sustains the finding of similar FCR.

Conventionally fed pigs – in comparison with organically fed pigs – clearly showed

better growth performance during first phase of fattening. This might be due to the

higher copper level in the conventional feed, which is known to act as a growth

promoter in piglets (Cromwell, 2001), but also because of the lower ileal digestible

lysine level in the organic feed. This agrees with research by Chiba et al. (1991) in

which pigs weighing 20 to 50 kg had increased weight gain with an increasing

lysine:energy ratio. As stated above, faster growth in the organically housed pigs has

urged a lysine requirement per energy unit that is similar to that of conventionally

housed pigs, despite the elevated energy demands for thermoregulation and activity.

During the second phase, the effect of nutrition on FCR disappeared. This indicates

that lysine was not limiting for growth at that stage. Chiba et al. (1999) saw a better

feed utilisation efficiency with increasing lysine concentrations in the finishing diet.

Their diets were formulated on total lysine and DE concentration, whereas in the

present experiment the feeds were formulated to a digestible lysine content and NE. A

75

clear comparison is therefore not possible. Because the lowest lysine concentration in

their experimental diets was 7.4 g lysine/kg and the organic diet in the present

experiment still reached a total lysine concentration of 8.2 g/kg, they probably started

with a limiting digestible lysine concentration whereas the lysine level in the organic

feed of the present experiment was no longer limiting. The genotype used in the

present study tended to have fatter growth; hence, the lowest lysine concentration in

relation to energy was probably already sufficient to fulfil nutrient requirements for

the pigs.

Higher feed intakes with organic diet led to higher growth rates during the second

phase. Differences in palatability between the feeds cannot be excluded in this study

as the two different kinds of feed were formulated to certain nutrient needs, but with

separate ingredient matrices (organic versus conventional).

Despite faster growth in the organic housing, no significant differences were seen in

carcass lean meat percentage. The pigs of the organic barn had a higher fat thickness,

which suggest that the faster growth was a fatter growth, but this was compensated by

a higher meat thickness of these animals. Together with the reduced ham angle and

the shorter carcass length of these pigs, these parameters point towards a more

“compressed” pig in the organic barn. The shorter carcass length in the organic

housing group is consistent with results published by Enfält et al. (1993b), where the

same effect was noted on pigs walking 735 m a day,whereas Hale et al. (1986) found

no effect of exercise on a treadmill on carcass length.

The average lean meat percentage of about 56% is in accordance with results of Enfält

et al. (1997), who reported average lean meat percentages of 55.7 % for Duroc, and

59.2 % for Yorkshire pigs. In that study, the outdoor reared pigs had a lower fat

thickness and a higher meat percentage. They attributed the greater lean meat

percentage of the outdoor grown pigs to the lower daily gain of outdoor pigs, whereas

in the present study this was not the case. On the contrary, van der Wal et al. (1993)

and Hansson et al. (2000) found higher lean meat percentages on conventionally

fattened pigs than free range and organically grown pigs.

Organic feeding did not affect carcass composition, which agrees with findings of

Fischer and Lindner (1998). They have seen no differences in meat percentage of pigs

fed a conventional concentrate or an organic concentrate. Sundrum et al. (2000a), who

formulated organic diets with different protein sources to obtain a sufficient amino

acid supply, has seen no difference in meat percentage between a conventional diet

76

and an organic diet supplemented with faba beans and potato protein. In the present

experiment, the intramuscular fat content was higher in pigs fed the organic, thus low

digestible lysine feed. Despite a higher subcutaneous fat level, the intramuscular fat

level was lower in the organically housed pigs. An increase in intramuscular fat level

enhances the consumer’s acceptability of pork up to a level of 3.5% (Fernandez et al.,

1999b). Several studies suggest a favourable relationship between intramuscular fat

and the juiciness and tenderness of pork (Fernandez et al., 1999a; Hodgson et al.,

1991)

Both housing and nutrition had significant effects on the ultimate pH of the meat. The

ultimate pH was lower in the organic housing group and on the conventional feed.

Muscle glycogen content influences the ultimate pH: Warris et al. (1989)

demonstrated a negative correlation between liver glycogen and ultimate pH. Essén-

Gustavson et al. (1988) demonstrated that muscle glycogen content was higher in

moderately exercised pigs than in non-exercised pigs. In our experiment, muscle

glycogen content was not measured, but the pH values support this thesis. Studying

the effect of outdoor rearing, Enfält et al. (1997) noted more glycogen in the muscles

at slaughter and a significant lower ultimate pH in outdoor reared pigs in comparison

to conventional ones. On the other hand, Enfält et al. (1993b) saw no changes in

muscle pH or in glycogen content in animals walking 735 m/d, neither did Van der

Wal et al. (1993) nor Warris et al. (1983) respectively in free-range pigs and pigs in

an outdoor paddock. In the present study, an effect of nutrition on ultimate pH was

also seen, which was not noted in other studies (Fernandez and Tornberg, 1991). The

reason for the interaction of nutrition and housing on initial pH in the ham remains

unclear. It was not accompanied by similar effects in the loin. In the loin, the initial

pH was lower in the pigs from the organic barn, suggesting a higher risk for PSE in

those animals. However, the mean pH-values of all groups were reasonably good in

view of meat quality. As this was not accompanied by lower values in the ham of

organically grown pigs, no solid conclusion can be drawn.

There was no effect of housing type on water holding capacity, which agrees with

Warriss et al. (1983). Both nutrition and housing had significant influences on meat

colour. This was demonstrated by the CIELAB colour co-ordinates as well as with the

six-point Japanese pork colour scale. This can be attributed to different factors, as post

mortem glycolysis rate, intramuscular fat content, pigment level and oxidative status

of the pigment all influence muscle colour (Van Oeckel et al., 1999). The darker

77

(redder) colour of organically housed animals can probably be attributed to an

enlarged spontaneous activity, leading to an increased ratio of IIa- to IIb-fibres or an

increased mean fibre cross-sectional area, as was seen by Petersen et al. (1998a). IIa-

fibres contain more myoglobin. However, the numerically higher CIE L*-value in the

organically housed pigs eating the conventional feed was somewhat contradictory to

the other results, and could be explained by the numerically lower initial pH values in

this group.

Statistically significant differences were observed between the four groups in the

Kruskall-Wallis test for Japanese colour scale scores, but from the used non

parametric test, significant differences between each other were not seen. However,

the pigs in the organic barn on the organic nutrition showed by far the highest score,

thus indicating the darkest meat. A cumulative effect of housing and nutrition on

subjective colour score can thus be suggested. The Japanese colour scale scores were

consistent with both the results of the CIE L*-value and the CIE b*-value: the pigs in

the organic housing on the organic feed showed the reddest and the darkest meat,

while the pigs from that barn on the conventional feed had numerically high redness

scores, but also high lightness scores, indicating redder but paler meat.

Although the pigs in the organic barn were observed eating straw, and straw particles

were observed in the manure, the expected difference in apparent crude fibre

digestibility between the two barns was not demonstrated. The higher protein

digestibility in the conventional diet could be due to the use of synthetic amino acids

in this formulation. The difference in ash digestibility is probably due to a higher

digestible mineral supplementation in the conventional feed.

III.A.1.5. CONCLUSION

In conclusion, this trial shows that organic housing and nutrition can clearly affect

carcass and meat traits but do not necessarily have to induce poorer production

performance, as is often stated in practice. Further investigations should clarify the

impact of activity and thermoregulation on performance in fattening pigs and look

into the mechanism of increased feed intake.

78

79

III.A.2. EFFECTS OF ORGANIC VERSUS CONVENTIONAL HOUSING

AND NUTRITION FROM WEANING UNTIL SLAUGHTERING IN

TERMINAL CROSSBREED PIGS

ABSTRACT

The effects of organic nutrition on growth performance, meat and carcass traits in

either a conventional or an organic housing unit from weaning until slaughtering were

evaluated in terminal crossbreeds of a paternal line and a maternal 3-way crossbreed

of Seghers Hybrid (currently Rattlerow Seghers).

All pigs were reared in a conventional way from birth until weaning (4 weeks). One

week after weaning they were moved to either a conventional or an organic barn.

Eight pens of 4 pigs (2 barrows and 2 sows) were held in both housing types.

The study started when the pigs reached the age of ten weeks. Half of the groups in

each barn received a conventional diet, and the other half received an organic diet.

Both feeds were isocaloric, neither of them contained antibiotic growth promoters.

Three-phase feeding was applied. The organic housing led to a higher feed intake

throughout the experiment (P <0.001), which resulted in a faster growth (P <0.001)

but a lower meat percentage (P <0.05). Organic nutrition did not affect growth

performance and carcass quality. Neither organic nutrition nor housing led to relevant

differences in meat quality traits.

Keywords: housing, meat quality, nutrition, organic, performance, pigs

After:

S. Millet, K. Raes, W. Van den Broeck, S. De Smet, G.P.J. Janssens, 2005.

Performance and meat quality of organically versus conventionally fed and

housed pigs from weaning till slaughtering. Meat Science 69, 335-341.

80

III.A.2.1. INTRODUCTION

Organic farming in Europe has grown over the last years, although organic pig

farming forms a small segment (chapter I.A). Pigs in an organic system must have

access to an outdoor area and they should have more space allowance (Council of the

European Union, 1999). A dry resting area with a sufficient amount of litter has to be

provided. In this housing system, higher maintenance energy requirements due to

extra energy costs for activity and thermoregulation are hypothesized. Major

differences between organic and conventional nutrition are the ban on synthetic amino

acids and products of GMO origin. Antibiotic growth promoters are prohibited as

well. In present legislation, an organic feed has to consist of a minimum of 80 % of

organic feed ingredients, which limits the choice of ingredients. Due to particular

agricultural practices, organic feeds may differ in composition and the content of

minor constituents. E.g. Asami et al. (2003) found a higher total phenolic content in

some organic products, which could lead to a higher anti-oxidant activity of organic

ingredients. These factors might exert major or minor influences on pig production

characteristics. Previous research (chapter III.A.1) demonstrated influences of both

organic housing and nutrition from birth to slaughter on several meat quality

characteristics. This experiment was conducted to further evaluate the effects of

organic nutrition and housing on meat characteristics, especially meat colour and

colour stability of meat from pigs of a commercial line with an identical history from

birth until weaning.

III.A.2.2. MATERIAL AND METHODS

III.A.2.2.1. Animals and management

Pigs were terminal crossbreeds of a paternal line and a maternal 3-way crossbreed of

Seghers Hybrid (currently Rattlerow Seghers). The paternal line was a homozygous

stress resistant synthetic line. The sows 3-way cross was based on homozygous stress

resistant closed lines of Large White, Landrace and a synthetic line. Hence, the pigs

were all homozygous stress resistant. Since the genotype of the maternal and paternal

lines were known, it was not necessary to test the experimental pigs on stress

resistance.

81

All pigs were reared in an identical way from birth to weaning (4 weeks of age). One

week after weaning, 60 pigs were moved to the organic barn (OH) on the

experimental production site. Another group of 60 pigs was reared conventionally

(CH) at the same site. From weaning to the onset of the study all pigs received a

starter diet with similar nutrient content (9.5 MJ NEv/ kg, 9 g ID lysine/ kg), either a

conventional feed (CF) in the conventional barn or an organic feed (OF) in the

organic barn.

The study started when the pigs reached the age of ten weeks. From each group, a

group of 16 barrows and 16 gilts was selected to limit variation in initial weights (21

± 2 kg). They were randomly assigned to 1 of 8 pens (each with 2 barrows and 2

sows) in their respective housing type. Each pen was assigned to either a conventional

or an organic diet in a 2 x 2 factorial design with 4 groups of 16 pigs (Organic

housing, organic nutrition; organic housing, conventional nutrition; conventional

housing, conventional nutrition, conventional housing, conventional nutrition).

All pigs were dewormed at the beginning of the study by an Ivomec® injection. As in

conventional production systems, the CH-pigs were dewormed again after 2 months.

All pigs were vaccinated against Aujeszky’s disease.

Diets were changed to the second and third phase feed when the average weight

within a group reached 40-45 kg and 70-75 kg respectively. The animals were

slaughtered at an individual live weight between 105 and 110 kg. Before slaughtering,

feed was withdrawn overnight.

III.A.2.2.2. Housing

The CH pigs had an indoor area with a surface of 1 m² per animal whereas the OH

pigs had access to an indoor area of 2 m² per animal and an outdoor area of 2 m² per

animal.

The organic housing consisted of an outdoor area with a concrete floor and an indoor

area with straw bedding. The surface in the conventional pens consisted of 75% of a

concrete floor without straw bedding and of 25% of slats. The conventional housing

had climate control, whereas the organic barn had natural ventilation. Straw was

replaced twice a week. One self-feeder (four feeder holes) and one nipple waterer

were provided in each pen. Environmental temperature was recorded with electronic

devices every hour (Testostor, Testo B.V., Almere, The Netherlands).

82

III.A.2.2.3. Feed

The organic feed was formulated in accordance with the EC-guidelines on organic

farming (Council of the European Union, 1999). Ninety percent of feed ingredients

were produced following the regulations on organic farming, exceeding the minimum

norm of 80% required by national legislation. Hence, the organic feed formulation

anticipated expected future legislation.

The formulation and analyses of the feeds are presented in tables III.7 and III.8.

Nutrient requirements were set as in the experiment described in chapter III.A.1.

Ingredient composition was determined by least cost formulation depending on

availability of ingredients. A three-phase feeding was applied. Within each phase,

organic and conventional feeds were isocaloric. None of the feeds contained growth-

promoting antibiotics. Because of the hypothesized lower requirement of digestible

lysine per unit of energy, the organic feed was formulated to a 15% lower digestible

lysine content. Feeds were produced by Molens Dedobbeleer (Halle, Belgium) and

were subject to proximate analysis.

III.A.2.2.4. Slaughtering

Slaughtering was spread over 5 slaughter days, with pigs of different pens spread over

the slaughter days, based on their live weight. Animals were slaughtered at similar

live weight, and not at similar age, to avoid that differences in carcass weight

overruled other effects on carcass conformation or meat quality.

Pigs were brought in the morning (between 7:00 am and 8:00 am) to the nearby

abattoir of Ghent University (distance approximately 6 km) in groups of 6-13 animals

with a small truck provided with a relatively flat loading ramp. During the transport

and lairage time, pigs of different pens were mixed, thus interaction between

unfamiliar animals was possible with all transports. The average time between arrival

in the abattoir and the onset of slaughtering varied from 1 until 5 hours between

slaughter days. Pigs were slaughtered with 4 minutes intervals, hence lairage time

varied less within than between slaughter days. Pigs were slaughtered at random, so

that differences in lairage time between groups are limited. Pigs were bled in the

hanging position after electrical stunning on the floor with manually served tongs

(250V). Mean time difference between the end of the stunning phase and the moment

of sticking was generally between 20 and 40 seconds. Between 1.5 and 2 hours post

83

mortem, carcasses were placed in a conventional chilling room (2-4°C, 91-92%

relative humidity), where they remained until the following morning. The same

persons performed slaughtering over the different slaughter days.

Table III.7 Ingredient composition of the experimental diets (%)

Organic diets Conventional diets

Ingredient 20-45 kg 45-70 kg 70-105 kg 20-45 kg 45-70 kg 70-105 kg

Organic wheat - 9.8 - - - -

Organic barley - 14.7 20.1 - - -

Organic pea 12.6 20 13 - - -

Organic corn 20.3 19.7 20 - - -

Organic soybean 13.1 - - - - -

Organic wheat shorts 9.6 11.6 13 - - -

Non-GMO soybean - 6.1 5.5 - - -

Organic rye 33.1 7.4 17.5 - - -

Potato protein 3.2 2.4 2.1 - - -

Organic alfalfa - 5.1 5 - - -

Wheat - - - 24.5 29.7 29.6

Soybean - - - 21.1 15.5 8

Barley - - - 20.1 8.0 12.5

Corn - - - 20.0 23.4 20.0

Linseed cake 3.8 - - - - -

Wheat shorts - - - 10.1 14.9 20.0

Alfalfa - - - - - 4.5

Mineral and vitamin premix 1.2 1 1 1.5 1.2 1.2

Molasses 2 1.2 2 - - 1.5

Calcium carbonate 0.6 0.4 0.4 0.8 0.8 0.6

Wheat middlings - - - - 5.0 -

Soya oil - - - 1.0 - 0.5

Monocalcic phosphate 0.46 0.25 0.1 0.16 0.1

VitE/Se 0.2 0.2 0.1 0.1 0.1

NaCl 0.01 0.05 0.027 - - 0.09

L-lysine-HCl - - - 0.13 0.22 0.28

L-threonine - - - 0.04 0.07 0.1

DL-methionine - - - 0.01 0.02 0.028

84

Table III.8 Calculated (analysed) nutrient composition of the experimental diets

First phase 20-45 kg Second phase 45-70 kg Third phase 70-105 kg

Nutrient Organic Conventional Organic Conventional Organic Conventional

NEv’97a (MJ/kg) 9.4 9.4 9.1 9.1 9.0 9.0

ID LYSc (g/kg) 7.4 8.6 6.4 7.6 5.6 6.5

Dry matter (g/kg) 869 (880) 875 (870) 868 (871) 869 (875) 866 (883) 872 (878)

Crude ash (g/kg) 51 (49) 54 (51) 48 (49) 51 (41) 45 (41) 50 (44)

Crude fibre (g/kg) 42 (58) 37 (67) 51 (67) 37 (77) 50 (61) 49 (62)

Crude protein (g/kg) 175 (167) 185 (197) 162 (160) 165 (166) 151 (150) 144 (144)

Ether-extract (g/kg) 48 (54) 39 (36) 34 (41) 27 (32) 34 (40) 32 (43)

Ca (g/kg) 7.0 5.9 6.5 5.5 5.9 5.5

P (g/kg) 5.5 4.9 4.6 4.5 4.9 4.5

DPb (g/kg) 2.2 1.8 2.2 1.4 1.8 1.6

ID MET/ID LYSc 0.31 0.30 0.29 0.33 0.31 0.32

ID MET+CYS/ID LYSc 0.61 0.61 0.58 0.67 0.61 0.62

ID THR/ID LYSc 0.66 0.63 0.62 0.67 0.65 0.65

ID TRP/ ID LYSc 0.20 0.20 0.21 0.21 0.19 0.19

a NEv’97= net energy for production in pigs according to the Dutch CVB system 1998 bDP= digestible phosphorus ID LYS= ileal digestible lysine, ID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cystine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan

III.A.2.2.5. Measurements

III.A.2.2.5.1. Production characteristics

Pigs were weighed individually every three weeks and at changing of each feeding

phase. At that time, feed consumption per pen was measured. Before weighing, feed

was withdrawn overnight.

Average daily feed intake was computed as total feed consumed by the pen during a

phase divided by the sum of the days the animals of the group were present during

that phase. Average daily gain was computed per period as the difference between

starting and final weight of the animals of the pen divided by the days they were

present during that period. Feed conversion ratio during a period was calculated by

dividing the feed intake of a pen through the weight gain of the animals of the pen

during that period.

85

Average lean meat growth per pen was calculated over the experiment. For this, initial

lean meat content was estimated at 45% of live weight at start of the experiment,

according to Susenbeth and Keitel (1988). Lean meat content at slaughter was

calculated from the carcass measurements (see III.A.2.2.5.2). Average daily lean meat

growth was consequently calculated from (LMS-LMI)/N, with LMS= lean meat

content of a pen at slaughter; LMI= lean meat content of a pen at the onset of the

experiment; N= sum of the fattening days of the animals of the group.

III.A.2.2.5.2. Carcass measurements

In the abattoir, live weight and warm carcass weight were recorded. Muscle thickness

and fat thickness were measured using a CGM-device (“Capteur Gras-Maigre”; Sydel,

Lorient Cedex, France) in order to obtain the meat percentage (Council of the

European Union, 1997).

Ham angle was measured using an SKGII device (Eurocontroll Breitsameter GmbH,

Friedberg, Germany) as an indicator for carcass conformation.

At 40 min post mortem (pH1) and 24 h post mortem (pH2), the pH was measured in

the m. longissimus thoracis et lumborum (LT) around the 13th thoracic vertebra and

in the m. semimembranosus (SM) of both carcass sides. Conductivity (Pork Quality

Meter, PQM, Tecpro GmbH, Aichach, Germany) was measured at the same

anatomical locations before cutting. The average of the measurements on both carcass

sides for each animal was further used.

One day post mortem, a piece of the LT of the right side anterior to the last thoracic

vertebra was removed and sliced (2.5 cm thickness). One slice was used for

measuring water-holding capacity with the filter paper method as described by

Kauffman et al. (1986). This was performed 15 min after making the fresh cut. Fifteen

minutes later (hence 30 min blooming time), this same slice was used for colour

measurements by determining the CIELAB colour co-ordinates in quadruplicate with

a HunterLab Miniscan device (D65 light source, 10° standard observer, 45°/0°

geometry, 1 inch light surface, white standard; Hunter, Reston, USA). These values

are CIE L* (lightness), CIE a* (redness), and CIE b* (yellowness).

A second slice was used to assess drip losses as the proportionate weight loss after

hanging the meat sample in a plastic bag for 48° at 2°C (Honikel, 1987).

A third slice was used to determine colour and lipid stability. Samples were wrapped

in a thin oxygen permeable film and allowed to bloom for 1 hour and CIELAB colour

86

co-ordinates were measured on 1 (d1), 3 (d3), 6 (d6) and 9 (d9) days post mortem.

Samples were stored at 4°C under constant illumination from white fluorescent lights.

On d9, the slice was used to measure lipid oxidation. Lipid oxidation was determined

by measuring 2-thiobarbituric acid reactive substances (TBARS) using a modified

method of Tarladgis, Watts, Younathan & Dugan (1960) and was expressed as µmol

malondialdehyde produced per g muscle.

III.A.2.2.6 Statistical analysis

Data were analysed using variance analysis. For performance parameters, the model

included the fixed effects of housing, nutrition and the interaction term housing x

nutrition, considering the pen as the experimental unit. For the carcass and meat

quality traits, the animal was considered as the experimental unit, with fixed effects of

housing, nutrition, gender and their interaction terms; warm carcass weight was

included in the model as a covariate and the day of slaughtering was considered as a

random effect. Colour stability was analysed using repeated measures analysis with

fixed effects of housing and nutrition and warm carcass weight as a covariate.

III.A.2.3. RESULTS

The average temperature in the organic barn increased from 13°C during the first

phase to 15.5°C and 19.3°C during the second and third phase respectively. The

corresponding average outdoor temperatures were 10.5, 12.4 and 18.2°C. The

temperature in the conventional barn was on average 19.4, 21.3 and 22.2°C during the

first, second and third phase respectively.

Average initial body weight was 22 ± 2 kg in the organic and 24 ± 2 kg in the

conventional house. Average weight within a group when switching to second and

third phase feed was 42 ± 2 kg and 74 ± 5 kg in the organic house and 42 ± 4 and 73 ±

6 in the conventional house respectively.

Housing did not alter feed conversion ratio during the different stages. However, as

the pigs in the organic barn showed a higher feed intake, a faster growth was observed

(table III.9). An interaction between nutrition and housing on feed conversion ratio

was detected during the first stage (P<0.05). Pigs fed the conventional diet in the

conventional house showed a poorer feed conversion ratio in comparison to the other

three groups.

87

The organic housing led to a lower muscle thickness (P<0.05) and a higher fat

thickness (P<0.05) of the carcass, resulting in a considerably lower meat percentage

(P<0.05) of the animals. Nutrition did not affect carcass quality (table III.10).

The meat of the conventionally housed pigs showed a higher CIE a* value (P<0.05)

and a tendency to a higher (P<0.1) value CIE b* 24 hours after slaughtering, which

disappeared after 3 days, resulting in a significant time × housing interaction on CIE

a* (P<0.001) and CIE b* coordinate (P<0.01) (figure III.1). Other significant

influences of housing and nutrition on meat quality characteristics could not be

detected.

Slaughter day significantly affected muscle thickness (P<0.05), carcass length (P<

0.01), pH 24 hours post mortem in SM (P<0.001) and LT (P<0.001), conductivity in

SM (P<0.05) and LT (P<0.001) and the CIELAB colour values (P<0.05, <0.05 and

<0.001 for respectively CIE L*, CIE a* and CIE b*). Significant influences of warm

carcass weight on the measured parameters were not observed.

56789

10111213

1 3 6 9

days post mortem

CIE

a*

Organic housing

Conventional housing

Figure III.1 Differences between housing type on CIE a* value during 9 days of display

88

Table III.9 Effect of nutrition and housing on mean values for performance traits of organically (OH) versus conventionally (CH) housed pigs, fed either an organic

(OF) or a conventional (CF) diet

OH CH P-values

OF CF OF CF SEM Housing Nutrition Housing x Nutrition

Average daily feed intake (g/d) 1637 1746 1507 1615 28 0.006 0.017 0.982

Average daily gain (g/d) 708 758 659 653 15 0.006 0.360 0.248 First Phase 20-45 kg

Feed conversion ratio (g/g) 2.32 2.31 2.29 2.48 0.03 0.129 0.068 0.043

Average daily feed intake (g/d) 2444 2409 2118 2238 36 <0.001 0.084 0.005

Average daily gain (g/d) 851 866 735 769 16 <0.001 0.160 0.573 Second Phase 45-75 kg

Feed conversion ratio (g/g) 2.87 2.78 2.89 2.91 0.02 0.113 0.477 0.211

Average daily feed intake (g/d) 3125 3370 2740 2850 79 0.001 0.121 0.537

Average daily gain (g/d) 896 958 767 753 26 <0.001 0.399 0.186 Third Phase 75-110 kg

Feed conversion ratio (g/g) 3.49 3.52 3.58 3.80 0.07 0.233 0.418 0.52

Average daily feed intake (g/d) 2487 2581 2234 2329 41 <0.001 0.075 0.987

Average daily gain (g/d) 830 870 730 734 17 <0.001 0.211 0.299

Feed conversion ratio (g/g) 3.00 2.97 3.06 3.18 0.04 0.120 0.600 0.407 Total 20-110 kg

Average daily lean meat growth (g/d) 336 350 333 338 6 0.529 0.694 0.565

89

Table III.10 Effect of nutrition and housing on mean values for carcass and meat quality traits of organically (OH) versus conventionally (CH) housed pigs, fed

either an organic (OF) or a conventional (CF) diet

OH CH P-values

OF CF OF CF SEM Housing Nutrition Housing x Nutrition

Lean meat percentage (%) 52.9 51.9 57.4 56.9 1.1 0.022 0.277 0.638

Muscle thickness (mm) 54.6 57.8 63.2 62 0.8 0.011 0.519 0.188

Fat thickness (CGM, mm) 18.4 20.1 16 16.3 0.5 0.045 0.150 0.850

Distance first rib-pubic bone (cm) 79.8 80.3 79.4 79.4 0.3 0.952 0.804 0.446

Ham angle (°) 38.7 37.3 35.2 37.1 0.6 0.297 0.558 0.284

PH1 SM 6.41 6.28 6.24 6.2 0.03 0.308 0.273 0.810

PH2 SM 5.616 5.536 5.601 5.539 0.015 0.286 0.383 0.635

pH1 LT 6.164 6.163 6.000 6.075 0.024 0.206 0.172 0.297

PH2 LT 5.559 5.484 5.514 5.453 0.012 0.233 0.361 0.292

PQM SM (µS) 8.58 9.56 10.30 10.65 0.23 0.128 0.705 0.970

PQM LT (µS) 6.95 7.46 8.55 8.26 0.21 0.518 0.222 0.210

Drip losses (%) 7.3 7.7 7.8 6.4 0.3 0.521 0.278 0.339

Water uptake filter paper method (mg) 97 94 99 98 30 0.747 0.931 0.908

CIE L* 51.8 54.7 54.9 55.9 0.9 0.536 0.906 0.825

CIE a* 6.79 6.43 7.02 7.14 0.13 0.017 0.590 0.294

CIE b* 16.66 16.75 16.99 16.66 0.15 0.090 0.477 0.723

TBARS (µg malondialdehyde/g meat) 0.201 0.188 0.207 0.207 0.007 0.313 0.919 0.841

90

III.A.2.4. DISCUSSION

In contrast to the previously described experiment (chapter III.A.1), all pigs were grown in a

conventional way until weaning. Moreover, a commercial breed (terminal crossbred of

paternal and maternal lines of Seghers hybrid) was used for the experiment.

The higher feed intake overcompensated the extra energy requirements for activity and

thermoregulation, leading to faster growth. Hence, energy expenditure for maintenance and

for growth were both increased, which can explain the similar feed conversion ratio between

the two housing types. The higher feed intake and consequently faster growth in the organic

barn matches with the previous results, although in the present experiment the faster growth

led to a lower meat percentage.

Probably, the energy intake exceeded the maximal protein deposition ratio in this breed of

pigs. Indeed, the average daily lean meat growth did not differ significantly between both

housing types, indicating that the maximal protein deposition rate was already attained in the

pigs from the conventional system. As meat percentage did not differ significantly between

conventionally housed and organically housed pigs in the previous experiment (chapter

III.A.1), the choice of a genotype might be important in organic pig production.

The interaction of housing and nutrition on feed conversion ratio during the first phase of

growth does not match with previous research (chapter III.A.1). In the conventional barns, the

pigs on the conventional feed showed a high FCR during this phase, which cannot be

explained.

Organic nutrition did not affect carcass quality, corresponding with earlier research (Fischer

and Lindner, 1998).

Meat quality characteristics were not consistently affected by either housing or nutrition, in

contrast to the findings in chapter III.A.1. In the present experiment, the colour values after

one hour blooming time differed slightly between the groups, but disappeared in the

subsequent colour measurements and might therefore not be relevant.

Slaughter day has an important impact on meat quality traits (Casteels et al., 1995). Indeed, in

the present experiment, slaughter day significantly affected several meat quality traits which

might have overruled subtle differences between nutrition and housing types. Part of the

slaughter day variation in this trial might have been due to the difference in mean lairage time.

The breed that was used might be less sensitive to subtle changes in nutrition and housing in

this experiment in comparison with the cross of a Piétrain boar and a (Belgian Landrace x

Duroc) sow in previous research (chapter III.A.1). Moreover, differences in the previous

91

experiment might be due to rearing circumstances before weaning. Gentry et al. (2004)

observed effects of both birth environment and rearing environment on redness of the meat,

with a higher percentage of type I fibres in outdoor born pigs. Outdoor reared pigs showed a

shift from IIb and IIx fibres to IIa fibres. In the present experiment, all pigs were born in the

same environment, thus probably disabling differences. Furthermore, the outdoor housing

described by Gentry et al. (2004) was an alfalfa pasture with 212 m²/pig. This is in contrast

with the small outdoor area on concrete floor in this experiment. Hence, differences in rearing

environment from birth to weaning might be important concerning meat fibre type and

consequently meat colour. Gentry et al. (2002b) found no differences in colour or fibre type

distribution between conventional pigs and pigs with increased space, whereas Bridi et al.

(1998) observed redder meat in outdoor housed pigs on a pasture of 3600 m². Gentry et al.

(2002a) and van der Wal et al. (1993) found no effects of housing on meat colour. Haem

pigment was not different between confined, trained or group housed pigs in the experiments

of Petersen et al. (1997). Similarly, Enfält et al. (1993b) could not demonstrate an effect of

exercise on haem pigment. Therefore, literature is not consistent on exercise effects on meat

quality characteristics, indicating that other factors, like genetics, and slaughter day and

procedures might interfere.

III.A.2.5. CONCLUSION

Organic nutrition in comparison to conventional nutrition does not lead to important

differences in growth and carcass quality characteristics of fattening pigs. Organic housing

can elevate feed intake and consequently growth rate, with potentially lower meat

percentages. In the present experiment, with a commercial line of pigs, neither organic

housing nor organic nutrition led to relevant differences in meat quality characteristics.

92

93

III.B IMMUNOCOMPETENCE AND SELECTED METABOLIC PROPERTIES

Small changes in nutrients may be of critical importance in increasing susceptibility to

infectious challenges. Therefore, the question rises if organic feedstuffs differ in such a way

from conventional ingredients that they could alter the immune function.

Moreover, as organic housing differs at several points from conventional housing, it may

affect immune function as well.

In this chapter, the influence of organic housing and nutrition on immunocompetence and

some metabolic properties was observed. Immune responsiveness was measured by means of

the specific antibody response against intramuscularly injected thyroglobulin. In the pigs

described in chapter III.A.2, acute phase proteins were measured as an health indicator and

lactate values in the blood at slaughter as a metabolic parameter indicating the reactivity to the

stressful circumstances at slaughter. Performance effects were described in chapter III.A.2.

94

95

IMMUNOCOMPETENCE OF FATTENING PIGS FED ORGANIC VERSUS

CONVENTIONAL DIETS IN ORGANIC VERSUS CONVENTIONAL HOUSING

ABSTRACT

The effect of organic or conventional feeding on the immune response of pigs was determined

using organic or conventional housing in a pig fattening unit. The experimental design

involved four pens of four animals per housing and diet combination (organic housing and

organic nutrition; organic housing and conventional nutrition; conventional housing and

organic nutrition and conventional housing and conventional nutrition). The IgM, IgA and

IgG response against intramuscularly injected bovine thyroglobulin was determined as

indicators of the antigen-specific immune responsiveness. Some general health and welfare

related parameters were evaluated by measuring haptoglobin concentrations at selected times;

blood lactate concentration was measured at slaughter.

Conventional housing led to a higher IgG response three weeks after the first immunisation.

Organic housing led to lower haptoglobin and lower lactate concentrations at slaughter,

indicating a higher stress resistance in these pigs. No major differences between the two

feeding types were found. We conclude that the immune responses following either a

conventional or an organic diet are comparable, whereas organic housing can increase stress

resistance at slaughter compared to conventional housing.

Keywords: Pigs, Organic farming, Housing, Nutrition, Immunocompetence

After:

S. Millet, E. Cox, J. Buyse, B.M. Goddeeris, G.P.J. Janssens, 2004. Immunocompetence

of fattening pigs fed organic versus conventional diets in organic versus conventional

housing. The Veterinary Journal, in press.

96

III.B.1. INTRODUCTION

European legislation on organic livestock production (Council of the European Union, 1999)

includes concerns on the environment, production of safe and healthy food and animal

welfare. Major differences exist between organic and conventional production systems

including housing, nutrition and management procedures, including veterinary treatments.

Organic fattening pigs, for example, benefit from an increased space allowance in comparison

with conventional fattening pigs and must have access to an outdoor area.

The legislation prescribes that “systematic operations that lead to stress, harm, disease or the

suffering of animals during the production, handling, transport or slaughtering stages should

be reduced to a minimum” (Council of the European Union, 1999). Furthermore, the

prophylactic use of chemically synthesised allopathic medicinal products is not permitted in

organic farming. Prevention of disease must be through breed selection, housing and

management and nutrition (Council of the European Union, 1999). However, when animals

become sick or injured, they should be treated immediately.

The production of feed is strictly regulated. Organic feeds must consist of a minimum of 80%

of ingredients produced in accordance with the rules of organic farming. There is a strict ban

on growth promoting substances and products originating from genetically modified

organisms (GMO) are not allowed.

Specific nutrients can inhibit or enhance the immune response, but the immune system itself

can also affect nutrient requirements. For example, cytokine synthesis decreases whole body

protein synthesis, and several vitamins and trace minerals are known to have an impact on

immune function (Johnson et al., 2001). As organic diets are formulated to specific standards,

differences between organic and conventional diets can be found in terms of macronutrients

or micronutrients. Klasing (1998) stated that in poultry, subtle influences due to the level or

type of ingredients may be of critical importance in increasing susceptibility to infectious

challenges. By comparing some organically produced products with those produced by

conventional agricultural practices, Asami et al. (2003) found a higher total phenolic content,

which could lead to a higher anti-oxidant activity of organic ingredients.

In the present study, a comparison between an organic and a conventional feed was made in

either an organic or a conventional pig fattening barn to investigate the effects on

immunocompetence.

97

III.B.2. MATERIAL AND METHODS

The experiment was conducted in Merelbeke, Belgium, from February until July 2002. The

Ethical Committee of the Faculty of Veterinary Medicine at the Ghent University approved

the experimental procedures on the animals.

III.B.2.1. Animals and management

A crossbreed of a paternal line and a maternal 3-way crossbreed of Seghers Hybrid (currently

Rattlerow Seghers) was used. Two groups of 32 piglets were used. One group was reared

conventionally and housed in a conventional barn (CH), the other was reared and housed

according to the national legislation on organic farming (OH) (MD August 19th, 2000). All

pigs were born in a conventional nursery at the experimental farm site. At five weeks of age

(one week after weaning), the pigs allocated to the organic barn were moved to the organic

barn on the same site.

The experiments started when the pigs were 10 weeks of age (21±2 kg). Within each house,

there were eight pens with four animals in each. Each pen contained two gilts and two

barrows. In both houses, half of the pens received a conventional feed (CF) while the other

half received an organic feed (OF), providing 4 replicates per diet and housing combination.

All pigs were dewormed at the beginning of the study by injecting Ivomec® (Merial). As with

conventional production systems, the CH-pigs were also dewormed two months later. All pigs

were vaccinated against Aujeszky’s disease virus at the start of the study and again three

weeks later.

Diets were changed to the second and third phase feed when the average weight within a

group reached approximately 45 kg and 70 kg respectively. The animals were slaughtered at

an individual liveweight of 105-110 kg, at an average age of 27 weeks.

III.B.2.2. Housing

The CH pigs had an indoor area with 1 m² per animal whereas the OH pigs had access to an

indoor area of 2 m² per animal and an outdoor area of 2 m² per animal. The organic housing

provided an outdoor area with a concrete floor and an indoor area with straw bedding that was

replaced weekly. Seventy-five per cent of the surface in the conventional pens consisted of a

concrete floor without straw bedding with 25% slats. The conventional barn had climate

control, whereas the organic barn only had natural ventilation. One self-feeder (four feeder

holes) and one nipple drinker were provided in each pen. Environmental temperature was

recorded with electronic devices every hour (Testostor, Testo B.V).

98

III.B.2.3. Nutrition

The organic feed was formulated following EC-guidelines on organic farming (Council of the

European Union, 1999) and 90% of the ingredients were produced in accordance with these

regulations, thus exceeding the minimum norm of 80% required by national legislation.

The formulation and analyses of the feeds are presented in table III.7 and III.8 (chapter

III.A.2) Three-phase feeding was applied. Within each phase, organic and conventional feeds

were isocaloric. None of the feeds contained growth-promoting antibiotics.

The organic feed was formulated to a 15% lower ileal digestible lysine content, as it was

hypothesized that pigs in the organic house would spend more energy on walking and

thermoregulation, thus lowering the relative protein to energy ratio. In this way, an organic

feed was produced that would be more appropriate in an organic barn.

All feeds were produced by Molens Dedobbeleer and were subjected to proximate analysis.

III.B.2.4. Measurements

III.B.2.4.1. Thyroglobulin-specific antibodies

To determine the influence of feeding type on the antigen-specific immune response, the pigs

were immunized at 10 weeks of age (day 1) with bovine thyroglobulin, after which the

thyroglobulin-specific serum IgM, IgA and IgG responses were determined. All pigs were

injected intramuscularly (i.m.) with 1 ml of an emulsion of equal volumes of phosphate

buffered saline (PBS) containing 1 mg bovine thyroglobulin T-1001 (Sigma) and incomplete

Freund’s adjuvant. A second identical injection was given three weeks later. Blood samples

were drawn from the jugular vein at the onset of the experiment, and 3, 6 and 9 weeks post

immunisation. A final sample was collected at slaughter. After overnight incubation at room

temperature, the serum was separated and stored at -18°C until analysis.

Thyroglobulin-specific antibodies were measured in an indirect antibody ELISA. The ELISA

plates were coated with thyroglobulin at a concentration of 10µg/ml coating buffer

(carbonate-bicarbonate, 50mM, pH 9.4) for 2 h at 37°C. The remaining binding sites were

blocked overnight with 0.2% Tween 80 in PBS at 4°C. Then, sera diluted 1:15 in ELISA

dilution buffer were added for 1 h at 37°C, after which the plates were incubated for 1 h

respectively with an optimal dilution of anti-pig IgG, IgA or IgM specific Mab (Van Zaane

and Hulst, 1987), biotinylated rabbit anti-mouse immunoglobulins (Zymed Laboratories,

Sambio BV) and peroxidase conjugated streptavidin (DAKO, Prosan). Between each step, the

plates were washed with washing buffer (PBS +0.2% (v/v) Tween 20). Finally, ABTS-

99

solution containing H2O2 (Roche Diagnostics,) was added and after 30 min incubation the

optical density was measured with a spectrophotometer at 405 nm (OD405).

III.B.2.4.2. Haptoglobin

Serum levels of haptoglobin, an acute phase protein, were determined as a parameter related

to general health (Petersen et al., 2002a, b). The haptoglobin concentration was measured in

all serum samples using the Phase Range (Tridelta Development). A volume of 7.5 µl serum

(undiluted or 1:5 (vol:vol) diluted in PBS) was brought in a cup of a microtitre plate after

which 100 ml of a solution of equal volumes haemoglobin and haemoglobin diluent (Phase

Range) were added. At that moment, the absorbance was measured for the first time at 600

nm. Subsequently, 140 µl of chromogen and substrate in a ratio of 9:5 was added. After 5 min

at room temperature the absorbance was measured again at 600nm. The difference between

absorbance before and after colour reaction was calculated. Haptoglobin concentration was

calculated by using a standard curve made from a two-fold dilution of a haptoglobin standard

(2mg/ml).

III.B.2.4.3. Lactate

Pigs slaughtered in high stress circumstances show higher lactate concentrations at slaughter

(Warriss et al., 1994). As a measure of the ability to cope with stressful circumstances around

slaughtering in this experiment, blood lactate concentration was determined at slaughter.

Lactate concentration was measured on fresh stabbing blood with an Accusport apparatus

(Boehringer Mannheim).

III.B.2.5. Statistics

The kinetics of thyroglobulin-specific antibodies was analysed using a General Linear Model

(Repeated Measures Analysis of variance, SPSS 11.0.1 for Windows). Haptoglobin

concentration was first log transformed and then analysed in an identical way. The model

included the fixed effects of housing, nutrition and gender and their interaction terms. Lactate

concentration in blood taken at slaughter was analysed using variance analysis, including the

same fixed effects and their interaction terms.

100

III.B.3. RESULTS

The average temperature in the organic unit increased from 13°C during the first phase to

15.5°C and 19.3°C during the second and third phase, respectively. The corresponding

average outdoor temperatures were 10.5, 12.4 and 18.2°C. The temperature in the

conventional house was on average 19.4°C in the first phase, 21.3°C in the second phase and

22.7°C during the third phase of growth. Average initial body weight was 22 ± 2 kg in the

organic and 24 ± 2 kg in the conventional house. Average weight within a group when

switching to second and third phase feed was 42 ± 2 kg and 74 ± 5 kg in the organic house

and 42 ± 4 and 73 ± 6 in the conventional house respectively.

III.B.3.1. Thyroglobulin-specific antibodies

No interaction between housing and nutrition was noticed.

Housing had a significant effect on the thyroglobulin-specific IgG (P<0.001) and IgM (P=

0.032) responses, but thyroglobulin-specific IgA response was not different between housing

types (P= 0.299): IgG increased faster (three weeks after the first injection) to a plateau level

in the conventional housing, whereas the IgM level was only numerically higher in the

conventional house by six weeks after injection (figure III.2). Feeding type did not influence

the thyroglobulin-specific antibody response.

III.B.3.2. Haptoglobin

Feeding type did not affect the haptoglobin concentrations (P= 0.737) (figure III.3). An effect

of housing type on the haptoglobin concentration during the experiment was noted (P=

0.019), with higher haptoglobin levels at slaughter in the animals of the conventional unit.

101

Ig M

00,050,1

0,150,2

0,250,3

0,350,4

0 3 weeks 6 weeks 9 weeks abattoir

OD

(1/

15)

IgA

0

0,2

0,4

0,6

0,8

1

1,2

1,4

0 3 weeks 6 weeks 9 weeks abattoir

OD

(1/

15)

IgG

*

0

0,2

0,4

0,6

0,8

1

1,2

1,4

0 3 weeks 6 weeks 9 weeks abattoir

OD

(1/

15)

02

0 3weeks

6weeks

9weeks

abattoir

organic housing, organic nutrition

organic housing, conventional nutrition

conventional housing, organic nutrition

conventional housing, conventional nutrition

Figure III.2 The thyroglobulin-specific IgG, IgA, and IgM antibody response in the four treatment

groups.(x ± SEM) * P< 0.05. Pigs were injected with bovine thyroglobulin at the start of the experiment

and three weeks later.

a

abab

b

-1

-0,8

-0,6

-0,4

-0,2

0

0,2

0,4

0 w eeks 3 w eeks 6 w eeks 9 w eeks abattoir

log

(hap

togl

obin

con

cent

ratio

n)

OH,OFOH, CFCH, OFCH,CF

Figure III.3 Haptoglobin concentration in the four treatment groups (x ± SEM). Different indices indicate

significant differences by Scheffé’s post hoc test at the same time point.

102

III.B.3.3. Lactate

Feeding type did not influence plasma lactate concentration at slaughter. A clear effect of

housing on this parameter was however noted (P= 0.015). Plasma lactate concentration

remained lower in the animals from the organic house compared the animals from the

conventional house (figure III.4).

4

5

6

7

8

9

10La

ctat

e co

ncen

trat

ion

(mm

ol/l)

organic housing, organic nutritionorganic housing, conventional nutritionconventional housing, organic nutritionconventional housing, conventional nutrition

Figure III.4 Lactate concentration in the stabbing blood for the four treatment groups (x ± SEM)

III.B.4. DISCUSSION

The immunoglobulin response against bovine thyroglobulin can give an indication of the

ability to react against a foreign antigen. The differences in antibody responses between the

housing types show that housing did affect the Ig response against a novel antigen possibly

due to differences in infection pressure or climate differences, including environmental

temperature, allowance for spontaneous activity, stress level and history of the animals. The

IgG response increased faster in the conventional than in the organic house. Ekkel et al.

(1995) demonstrated that the ‘Specific-Stress-Free’ housing system elicited a higher

immunoglobulin response on an intradermally injected phytohaemagglutinin. In this kind of

housing, all possible stressors such as mixing or temperature stress are avoided.

Although organic housing is intended to meet the natural behaviour of the animals, it cannot

be considered to be stress-free. Moving the pigs to the organic barn at five weeks of age, in an

environment with a lower temperature, is likely to be a stressful event (Kelley, 1980) and will

contribute to a slower immune responsiveness, explaining, at least in part, the slower kinetics

of the immune response in the organic house in comparison with the conventional barn.

103

Differences in antibody response between the feeding types were not seen in our study. These

findings lead to the conclusion that other factors such as management measures rather than

organic nutrition can affect antigen-specific immune response.

The acute phase response is part of the early defence mechanism in animals following

infection, inflammation or trauma (Eckersall et al., 1996; Petersen et al., 2002a, b) and is

mediated by pro-inflammatory cytokines such as IL-1, IL-6 and TNF inducing amongst others

acute phase proteins (Baumann and Gauldie, 1994; Eckersall, 2000). Haptoglobin, an acute

phase protein, can give an indication of the health status of an individual (Petersen et al.,

2002a) or herd (Petersen et al., 2002b).

As already mentioned, pigs in an organic house can benefit from an elevated space allowance

in comparison with conventional finishing pigs and from access to an outdoor area.

Air volume and stocking density are risk factors influencing respiratory diseases (Stark,

2000), hence the organic pigs were probably at lower risk. However, as haptoglobin

concentration did not differ during the experiment, we cannot conclude that there was a

difference in health status whereas the higher haptoglobin concentration at slaughter could

have resulted from preslaughter handing.

Feeding type did not affect haptoglobin concentration, suggesting that housing and

management are of greater importance in the development and evolution of the immune

response than subtle differences between an organic and a conventional diet.

The larger space allowance could increase the spontaneous activity of the organic pigs. With

increasing fitness, muscles generate less ATP through anaerobic pyruvate catabolism, which

reduces lactate formation following physical stress (Jorgensen and Hyldgaard-Jensen, 1975).

The animals from the organic house had lower blood lactate levels at slaughter and might thus

have spent less energy during the preslaughter treatment. Indeed, the lower plasma lactate

concentration in the OH pigs might be due to a better ability to cope with the stressful

conditions around slaughtering.

The lower blood lactate concentration and haptoglobin concentration at slaughter in the pigs

from the organic house might indicate that these pigs had become more resistant to stressful

circumstances around slaughter.

Although from this experiment, differences between production types cannot be attributed to

one specific element, differences in housing and management did affect immune and stress

parameters to a greater extent than nutrition type.

104

III.B.5. CONCLUSION

Organic housing conditions exerted moderate differences in immune response in fattening

pigs in comparison to those reared under conventional housing conditions. It appears that OH

pigs are better adapted to stressful conditions such as those accompanying the manipulations

before slaughter. Applying a conventional or an organic diet had no effect on any

immunological or stress parameters measured. If an organic diet is supposed to enhance the

resistance against infection, sources of typical immunostimulating substances might have to

be included in the diet.

105

CHAPTER IV. APPLICATION OF CCM IN ORGANIC PIG FATTENING

In chapter III, the feasibility of pig production with organic housing and nutrition without

losses in production characteristics was demonstrated. However, the cost is rather high.

Especially the feed cost is very high. Moreover, the use of organic concentrates with

ingredients from far abroad might raise problems concerning sustainability. Therefore,

products of local origin will fit better into the scope of a sustainable organic agriculture. This

might probably lower the cost. Therefore, the usefulness of corn cob mix (CCM) in organic

fattening pig nutrition was evaluated. This is a product that can be produced in a fairly easy

way in Belgium. The use of this semi-moist product might have an extra beneficial effect

when looking to the results of the first experiments. Namely, when the high feed intake goes

beyond the capacity of protein deposition in pigs, this may lead to fatter carcasses. Therefore,

the water content of the feed, leading to a lower energy density on a fresh matter base, might

limit the daily energy intake.

The use of CCM is already applied in some conventional production systems. However, apart

from some German papers (Kracht et al., 1984; Wecke et al., 1990), the scientific information

on this product is limited.

In the next chapters, the results of two experiments with CCM are presented. Analogous to

the first part of the thesis, the first evaluation was related to performance and product quality.

In a second part, the influence of CCM inclusion in the diet on thyroglobulin-specific

antibody response is discussed. For formulation of the feeds, the protein:energy ratio as

obtained in chapter II was used. One feed was used from 45 kg until slaughtering with a

protein:energy ratio similar to the second phase MP feed. As the protein content has been

shown to be limiting during the first phase of growth, the use of the low-protein feedstuff

CCM was evaluated in these experiments from 45 kg until slaughtering.

106

107

IV.A. EVALUATION OF CCM IN ORGANIC FINISHING PIG NUTRITION ON

PERFORMANCE AND PRODUCT QUALITY

ABSTRACT

Two consecutive experiments were performed to evaluate corn cob mix (CCM) inclusion in

an organic diet. The experiments were performed in an organic barn with 9 pens of 4 pigs (2

barrows and 2 sows) of commercial breeds from 45 kg to slaughter. In the first CCM

experiment (exp. CCM1), an organic concentrate was mixed with organic CCM-silage to

obtain three concentrate:CCM ratios of 100:0, 80:20 and 60:40 (w:w). In the second CCM

experiment (exp. CCM2), three concentrates were produced to obtain diets with equal nutrient

levels on a dry matter basis after 0%, 20% and 40% CCM inclusion respectively.

In all groups of both experiments, meat and carcass traits were comparable to common

practice and differences between treatment groups were not seen. Feed conversion ratio on an

as fed basis was worse with higher CCM percentages in the diet, most likely due to the

dilution effect by the lower dry matter content of CCM. In exp. CCM1, pigs on a lower

concentrate:CCM ratio showed a higher feed intake, indicating a compensation for the lower

energy density of these diets. In exp. CCM2, the 40% CCM group showed a lower daily dry

matter intake (P= 0.048) leading to a slower growth (P= 0.015). This indicated a bulk-effect

of the CCM in this case. In conclusion, lean carcasses with good meat quality can be obtained

even in situations where up to 40% organic CCM-silage is included in a balanced organic pig

fattening diet. Moreover, a bulk effect of CCM-silage can be used in some cases to limit the

typically high dry matter intake in outdoor pig fattening, thereby preventing excessive fat

accretion.

Keywords: Corn cob mix, finishing pigs, growth, meat quality, performance

After:

S. Millet, K. Raes, S. De Smet, G.P.J. Janssens. Evaluation of Corn Cob Mix in organic

finishing pig nutrition, 2004. Journal of the Science of Food and Agriculture, accepted.

108

IV.A.1. INTRODUCTION

Organic animal production is expanding in the European Union since animal welfare and

environmental concerns are gaining interest. Organic pig feeds still often contain feedstuffs

that – although from organic origin – are imported from far abroad, which disagrees with the

idea of sustainable agriculture. Feedstuffs from local origin would better fit within the scope

of organic agriculture. CCM might be a practical ingredient from local origin that can be

included at fairly low cost. CCM is semi-moist product, which can easily be stored as silage.

The main differences with concentrate feeds are lower dry matter content and unbalanced

protein to energy ratio. Therefore, the question rises if this ingredient can e used in feed

formulation without affecting performance an product quality. Feed intake in an organic pig

fattening barn was shown to be considerably higher in comparison to conventionally housed

pigs (chapter III.1). This may lead to an extra amount of fat deposition (Olsson et al., 2003),

especially when the maximal capacity for protein accretion is exceeded. Therefore, it may be

beneficial to lower feed intake to a level below the maximal capacity for protein deposition in

finishing pigs.

The semi-moist nature of CCM might cause a bulk effect, and therefore increase satiation. If a

bulk effect is attained, the feed intake may go down and the energy intake might be limited.

This could alter performance and carcass quality.

The aim of the present study was to determine the effect of organic CCM-silage in voluntary

intake of feed, dry matter and energy in an organic pig fattening barn, and the consequences

for performance, carcass and meat quality.

IV.A.2. MATERIAL AND METHODS

Two experiments were conducted in an organic barn. In exp. CCM1, a commercial organic

feed was mixed with organic CCM-silage at concentrate:CCM ratios of 100:0, 80:20 or 60:40

(w:w). In exp. CCM2, three diets were formulated with similar nutrient contents, but with

inclusion of 0%, 20%, or 40% organic CCM-silage. In this way, the effects of CCM inclusion

could be separated from other factors. More in specific, the effect of CCM supplementation

was evaluated without other changes in feed matrix in the first experiment but this led to

changes in amino acid and premix concentration. In the second experiment, these factors were

held constant, leading to differences in the feed matrix, other than CCM.

109

IV.A.2.1 Animals and management

In each experiment, a group of 36 pigs of a commercial breed was randomly divided over 9

pens of 4 pigs in an organic production unit (2 barrows and 2 sows per pen). Pigs were a cross

of a Piétrain boar and a (Yorkshire×DL) sow in exp. CCM1 and the animals were terminal

crossbreeds of a paternal line and a homozygous stress resistant maternal 3-way crossbreed of

Rattlerow Seghers in exp. CCM2. The paternal line was a Piétrain based stress susceptible

line.

The pigs were kept according to conventional husbandry practices until weaning (4 weeks of

age). One week after weaning they were moved to the organic barn at the experimental

production site and grown according to organic production rules.

Each group of 4 pigs had access to an outdoor area of 8 m² with a concrete floor and an indoor

area of 8 m² bedded with straw. The barn was naturally ventilated and straw was replaced

twice a week. Housing was in accordance with the EC-regulations on organic production3.

One self-feeder (four feeder holes) and one nipple waterer were provided in each pen.

Environmental temperature was recorded using electronic devices every hour (Testostor,

Testo Ltd., Almere, The Netherlands).

All pigs received the same organic starter diet (9.5 MJ NEv, 9 g ileal digestible (ID)

lysine/kg) from weaning until 20 kg BW, and growing diet (9.6 MJ NEv, 8 g ID lysine/kg)

from 20 to 45 kg BW. At an average BW of 44 ± 5 kg (about 15 weeks of age), the

experiment started. At that moment, all pigs were dewormed (Ivomec®, Merial) and

vaccinated against Aujeszky’s disease.

Each pen was randomly assigned to one of three dietary treatment groups (description of

diets: see below).

In exp. CCM1, pigs were slaughtered when their individual BW reached between 100 and 105

kg, with an average weight of 103 ± 4 kg. This took 4 slaughter days, but each slaughter day

included pigs of all three treatment groups. In exp. CCM2, all animals were slaughtered at the

same day, with an average weight of 105 ± 7 kg. Feed was withdrawn overnight before

slaughtering. The pigs were transported to the nearby experimental slaughterhouse (8 km) in

groups of 12 animals at most. The time between arrival at the slaughterhouse and slaughtering

varied from 1 to 5 hours. Pigs were bled in the hanging position after electrical stunning on

the floor with manually served tongs (250V). Mean time difference between the end of the

stunning phase and the moment of sticking was generally between 20 and 40 seconds.

Between 1.5 and 2 hours post mortem, carcasses were placed in a conventional chilling room

110

(2-4°C, 91-92% relative humidity), where they remained until the following morning. The

same persons performed slaughtering over the different slaughter days.

IV.A.2.2 Feed composition

IV.A.2.2.1 Experiment CCM1

Per treatment, one feed was used from 45 to 105 kg BW. An organic concentrate was mixed

with organic CCM-silage to obtain three concentrate:CCM ratios of 100:0, 80:20 and 60:40

(w:w). Based on earlier research (chapter II), the concentrate was formulated to exclude

amino acid deficiencies, even in the 40% group (table IV.1). The feed was formulated in

accordance with EC guidelines on organic production (Council of the European Union, 1999).

The CCM was produced according to organic legislation (Council of the European Union,

1991) and ensiled with a plastic seal. For the appropriate use of small amounts of CCM, it

was re-ensiled in barrels of approximately 170 kg. The concentrate was produced by Molens

Dedobbeleer (Halle, Belgium) and was subject to proximate analysis (AOAC, 1980).

IV.A.2.2.2 Experiment CCM2

Per treatment, one feed was used from 45 to 105 kg BW. Three concentrates (A, B and C)

were produced to obtain diets with similar nutrient demands on a dry matter basis when

respectively 0, 200 or 400 g/kg CCM was included in the total diet on an “as fed” basis (table

IV.2). Therefore, on a dry matter basis, 0%, 15.2% and 32.3% CCM was included [(20 x

0.63)/(80 x 0.88 + 20 x 0.63)= 15.2 and (40 x 0.63)/(60 x 0.88 + 40 x 0.63)= 32.3]. The feed

was formulated in accordance with EC guidelines on organic production (Council of the

European Union, 1999)

The CCM used in this experiment was the same as the CCM used in the exp. CCM1.

Concentrates were produced by Molens Dedobbeleer (Halle, Belgium) and were subject to

proximate analysis.

111

Table IV.1 Ingredient composition and computed (analysed) nutrient content of the concentrate in exp.

CCM1 and the corn cob mix (CCM)*

concentrate CCM

NEv’97# (MJ/kg) 8.7 (8.9) 7.2†

Dry matter (g/kg) 882 (901) (634.3)

Crude ash (g/kg) 68 (59) 12.7 (11.6)

Crude fibre (g/kg) 60 (77.2) 28.4 (28.5)

Crude protein (g/kg) 223 (227) 58.3 (53.2)

Ether-extract (g/kg) 43 (56) 27.0 (37.2)

ID LYS£ (g/k) 9.1 0.89

ID MET+CYS / ID LYS£ 0.30 2.0

ID THR/ ID LYS£ 0.66 1.39

ID TRP/ ID LYS£ 0.24 0.24

Organic wheat (%) 22.8

Organic peas (%) 22.5

Linseed expellers (%) 18.5

Organic barley (%) 7.5

Non gmo soybeans (%) 7.25

Organic soybean cake (%) 6.3

Organic alfalfa (%) 4.5

Organic wheat shorts (%) 3.25

Potato protein (%) 1.9

Mineral and vitamin premix°(%) 1.8

Molasses beet (%) 1.5

Calcium carbonate (%) 0.76

Organic corn (%) 0.75

Monocalcic phosphate (%) 0.33

VitE/Se (%) 0.3

NaCl (%) 0.13 * CCM value as published by DSM Nutritional Products (CCM, 40% core), calculated to a dry matter content of 63.4%. # NEv’97= net energy for production in pigs according to the Dutch CVB system 1998 † Table value calculated for a 63% dry matter basis. £ ID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cysteine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan and ID LYS= ileal digestible lysine ° Vit A: 1000 IU/g; Vit D3: 200 IU/g; Vit E: 4 mg/g; Vit K3: 0.22mg/g; Vit B1: 0.16 mg/g; Vit B2: 0.38 mg/g; Vit PP: 2.4 mg/g; Vit B6: 0.23 mg/g; Folic acid: 0.08 mg/g; Vit B12: 0.0024 mg/g, Vit H: 0.008 mg/g; Fe++ 1%, Cu++ 0.08%, Mn: 0.7%; Co: 0.004%; Zn: 0.8%; I: 0.004%, Se: 0.0032%, Choline: 35 mg/g; Ca: 19.25%; Na: 8.9%, Mg: 1.1%; Endo-1,4-beta-xylanase F.C. 3.2.1.8. 0.8 IU/g

112

Table IV.2 Ingredient composition and computed (analysed) nutrient content of the 3 experimental diets

of exp. CCM2 on an equal dry matter basis

Concentrates

A° B° C°

NEv’97* (MJ/kg) 9.20 9.20 9.20

Dry matter (g/kg) 875 (887) 878 (887) 881 (879)

Crude ash (g/kg) 51 (72) 51 (62) 52 (53)

Crude fibre (g/kg) 54 (115) 58 (76) 59 (60)

Crude protein (g/kg) 175 (204) 175 (175) 176 (181)

Ether-extract (g/kg) 42 (54) 42 (50) 44 (46)

ID LYS# 6.53 6.53 6.53

ID MET+CYS / ID LYS# 0.68 0.66 0.66

ID THR/ ID LYS# 0.68 0.67 0.67

ID TRP/ ID LYS# 0.23 0.22 0.22

Organic triticale (%) 21.57 15.24 17.81

Organic corn (%) 20.00 10.14 0.00

CCM (%)† 0.00 15.20 32.30

Organic peas (%) 15.70 20.00 20.00

Organic barley (%) 10.00 10.00 -

Non GMO soy bean (%) 9.20 8.95 8.34

Linseed expellers (%) 7.79 9.62 10.78

Organic alfalfa (%) 6.00 6.00 5.13

Organic wheat shorts (%) 5.39 2.33 1.37

Organic soybean cake (%) - - 2.16

Potato protein (%) 1.26 0.53 -

Mineral and vitamin premix (%) 1.20 1.20 1.20

Beet molasses (%) 1.00 - -

Calcium carbonate (%) 0.34 0.37 0.43

Monocalcic phosphate (%) 0.30 0.25 0.20

VitE/Se (%) 0.20 0.20 0.20

NaCl (%) 0.05 0.07 0.08

°concentrate A: as fed; concentrate B: to be mixed with CCM in a concentrate:CCM ratio of 80:20; concentrate C: to be mixed with CCM in a concentrate:CCM ratio of 60:40 *NEv’97= net energy for production in pigs according to the Dutch CVB system 1998. #ID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cysteine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan and ID LYS= ileal digestible lysine † Percentage CCM calculated on an 88% dry matter basis, and thus not as-fed. °Vit A: 1000 IU/g; Vit D3: 200 IU/g; Vit E: 4 mg/g; Vit K3: 0.22mg/g; Vit B1: 0.16 mg/g; Vit B2: 0.38 mg/g; Vit PP: 2.4 mg/g; Vit B6: 0.23 mg/g; Folic acid: 0.08mg/g; Vit B12: 0.0024mg/g; Vit H: 0.008 mg/g; Fe++ 1%, Cu++ 0.08%, Mn: 0.7%; Co: 0.004%; Zn: 0.8%; I: 0.004%, Se: 0.0032%, Choline: 35 mg/g; Ca: 19.25%; Na: 8.9%, Mg: 1.1%; Endo-1,4-beta-xylanase F.C. 3.2.1.8. 0.8 IU/g

113

IV.A.2.3 Measurements

IV.A.2.3.1 Production traits

Every 3 weeks, pigs were weighed individually. Average daily feed intake (ADFI) was

computed as total feed consumed by the pen during a feeding phase, divided by the number of

pig-feeding days during that phase. The average daily gain (ADG) was computed per feeding

phase as the difference between the final and initial weight of the pen divided by the number

of pig-feeding days during that phase. Feed conversion ratio (FCR) was calculated on pen

basis.

In order to make an estimation of the NE content of the CCM, feed energy conversion ratio in

exp. CCM1 (computed as NE of the feed x FCR) was assumed to be constant, as protein

content was not limiting for growth.

IV.A.2.3.2 Carcass composition and meat quality

At the abattoir, live weight and warm carcass weight were recorded. Muscle thickness and fat

thickness were measured using a PG200-device (Giralda Choirometer PG 200, Eurocontroll

Breitsameter GmbH, Aichach, Germany) to obtain the carcass lean meat percentage (Council

of the European Union, 1997). Carcass yield was measured as warm carcass weight over live

weight at slaughter.

pH was measured 40 min (pH1) and 1 day (pH2) post mortem in the loin around the 13th

thoracic vertebra (m. longissimus thoracis et lumborum) and in the ham (m.

semimembranosus) of both carcass sides. In the same anatomical locations, conductivity

(Pork Quality Meter, PQM, Tecpro GmbH, Aichah, Germany) was measured 1 day post

mortem. The average of the measurements on both carcass sides for each animal was

calculated for analysis.

Following the carcass measurements at 1 day post mortem, a piece of the loin of the right

carcass side anterior to the last rib was removed and sliced. One slice was used for colour

measurements. Hereto the CIELAB colour co-ordinates (CIE L*, CIE a*, CIE b* values)

were determined in quadruplicate with a HunterLab Miniscan device after a 30-minute

blooming time (D65 light source, 10° standard observer, 45°/0° geometry, 1 inch light

surface, white standard; Hunter, Reston, USA). In addition, the water-holding capacity of the

same slice was measured with the filter paper method described by Kauffman et al. (1986)

A second slice was used to assess drip losses as the proportionate weight loss after hanging

the meat sample in a plastic bag for 48° at 2°C (Honikel, 1987).

114

IV.A.2.4 Statistical analysis

Data were analysed using variance analysis (SPSS 12.0 for Windows, SPPS Inc., Illinois,

USA). For performance parameters, the fixed effect of %CCM was included, with pen as the

experimental unit. When visually a linear relationship was observed, a linear regression

analysis was performed. For the carcass and meat quality traits, variance analysis was

performed. The model included fixed effects of %CCM and gender and their interaction,

considering the animal as experimental unit. Carcass weight was included as a covariable and

the day of slaughtering was considered as a random effect (in exp. CCM1).

IV.A.3. RESULTS

IV.A.3.1 Experiment CCM1

Average indoor and outdoor temperature during exp. CCM1 were 20 ± 4°C and 17 ± 6°C,

respectively.

The concentrate:CCM ratio did not influence the measured meat and carcass traits

significantly (table IV.3).

115

Table IV.3 Meat and carcass traits of organic fattening pigs fed different concentrate:CCM ratios (exp.

CCM1; n= 12 per treatment group)

Concentrate:CCM ratio (w:w)

100:0 80:20 60:40 SEM P

Carcass yield (%) 82.8 83.8 83.1 0.5 0.192

Muscle thickness (mm) 62.6 62.4 61.8 1.1 0.812

Fat thickness (mm) 14.7 17.3 15.7 0.7 0.157

Lean meat percentage (%) 60.2 58.0 59.1 0.8 0.383

pH1 ham 6.14 5.99 6.08 0.04 0.442

pH1 loin 6.05 6.04 6.08 0.02 0.889

pH2 ham 5.63 5.64 5.63 0.02 0.827

pH2 loin 5.53 5.53 5.55 0.01 0.658

PQM ham*(µS) 10.4 9.7 9.8 0.3 0.643

PQM loin*(µS) 9.7 9.4 8.8 0.2 0.659

Drip losses (%) 13.3 13.3 11.5 0.7 0.634 Water uptake filter paper method (mg) 128 121 115 3 0.587

CIE L* # 59.4 60.1 56.6 0.9 0.458

CIE a* # 6.5 6.0 6.9 0.2 0.579

CIE b* # 15.9 15.8 15.6 0.2 0.743 *Conductivity measured with a Pork Quality Meter (Tecpro GmbH, Aichach, Germany) # CIE L* (lightness), CIE a* (redness), and CIE b*(yellowness): CIELAB colour co-ordinates measured in quadruplicate with a HunterLab Miniscan device after a 30 min blooming time (D65 light source, 10° standard observer, 45°/0° geometry, 1 inch light surface, white standard; Hunter, Reston, USA).

Gender clearly affected fat thickness of the carcass (P<0.001) and lean meat percentage

(P<0.001) as well as drip losses (P= 0.007). The sows showed lower fat thickness and a

higher meat percentage in comparison to the barrows. Barrows showed lower drip losses. The

day of slaughter affected muscle thickness (P= 0.004) and tended to affect meat percentage

(P= 0.081). PQM in the ham (P<0.001) and CIE L*-value 24 hours (P= 0.009) post mortem

were also different throughout the slaughter days. Still, all slaughter day effects were random.

Weight at slaughter influenced muscle thickness, with increasing muscle thickness at higher

weights (P<0.011).

On a dry matter basis, FCR was numerically lower with decreasing concentrate:CCM ratios

(r= 0.388, P= 0.302 with linear regression analysis).

116

A positive linear relationship between CCM percentage and FCR on an as fed basis was

detected (r= 0.757, P= 0.018) with linear regression analysis, although ANOVA analysis

revealed a P-value>0.05 (table IV.4).

Table IV.4 Performance of organic fattening pigs from 45 kg to slaughtering fed different

concentrate:CCM ratios (exp. CCM1; n= 3 per treatment)

Concentrate:CCM ratio (w:w)

100:0 80:20 60:40 SEM P Average daily feed intake (g/d) 2445 2634 2722 59 0.135

Average daily gain (g/d) 843 876 855 15 0.717

Average daily dry matter intake (g/d) 2203 2233 2162 38 0.793

Feed conversion ratio (g/g) 2.90 3.01 3.19 0.05 0.072

Feed conversion ratio (dry matter basis g/g) 2.62 2.55 2.53 0.03 0.590

Average daily dry matter intake did not differ between the treatment groups.

ADFI tended to rise with a higher CCM level, with again a positive linear relationship in a

linear regression analysis (r= 0.683, P= 0.042). Average daily gain did not differ significantly

between the groups.

Assuming feed energy conversion ratio to be constant, the feed energy conversion ratio of the

concentrate feed (8.9*2.8914) was compared with the feed energy conversion ratio of the 20%

group. The latter was calculated as feed conversion ratio obtained by the regression curve

(0.0071*20+ 2.8914) * NE content of the diet with the 80:20 ratio. This led to an estimated

NE of the CCM (X) from the equation (1): 2.8914*8.9= (0.0071*20 + 2.8914)*(0.8*8.9 +

0.2*X).

Hence, the estimated net energetic value of the CCM-silage was 6.96 MJ/kg.

IV.A.2.2 Experiment CCM2

Average indoor and outdoor temperature during exp. CCM2 were 16 ± 4°C and 12 ± 5°C.

CCM percentage did not influence the measured meat and carcass traits significantly (table

IV.5). Gender affected fat thickness of the carcass (P= 0.001), lean meat percentage (P=

0.002) and PQM in the ham (P= 0.007). Sows showed lower fat thickness and higher lean

meat percentage. PQM in the ham was lower in sows. Weight at slaughter increased muscle

(P= 0.012) and fat thickness (P= 0.004).

117

On a dry matter basis, the FCR did not differ between the treatment groups. The level of

CCM inclusion elevated FCR on an as fed basis (table IV.6) (r= 0.910, P= 0.001).

Average daily dry matter intake was affected by the percentage CCM included, with

numerically lower values on the 40% CCM feed (r= 0.671, P= 0.048). In analogy, a

significant decrease in ADG with increasing CCM inclusion was noted (r= 0.770,P= 0.015).

Table IV.5 Effect of the percentage of corn cob mix (%CCM) included in a diet on carcass and meat

traits of organic fattening pigs (exp. CCM2; n= 12 per treatment)

% CCM inclusion

0 20 40 SEM P

Carcass yield (%) 81.8 81.3 81.9 0.3 0.586

Muscle thickness (mm) 66.5 63.1 62.3 1.3 0.481

Fat thickness (mm) 12.7 12.2 12.8 0.5 0.396

Lean meat percentage (%) 61.7 61.4 60.6 0.5 0.543

pH1 ham 6.27 6.26 6.25 0.03 0.978

pH1 loin 6.04 6.09 6.07 0.02 0.432

pH2 ham 5.74 5.69 5.66 0.03 0.701

pH2 loin 5.49 5.48 5.45 0.01 0.780

PQM ham*(µS) 10.19 10.64 10.57 0.28 0.770

PQM loin*(µS) 10.06 10.70 10.16 0.31 0.674

Drip losses (%) 5.74 6.55 7.02 0.42 0.527

Water uptake filter paper method (mg) 0.107 0.106 0.108 0.003 0.903

CIE L* # 57.7 57.3 56.8 0.7 0.910

CIE a* # 7.06 7.4 7.43 0.14 0.478

CIE b* # 15.79 15.81 15.91 0.15 0.665 *Conductivity measured with a Pork Quality Meter (Tecpro GmbH, Aichach, Germany) # CIE L* (lightness), CIE a* (redness), and CIE b*(yellowness): CIELAB colour co-ordinates measured in quadruplicate with a HunterLab Miniscan device after a 30 min blooming time (D65 light source, 10° standard observer, 45°/0° geometry, 1 inch light surface, white standard; Hunter, Reston, USA).

118

Table IV.6 Effect of the percentage of corn cob mix (%CCM) included in an organic pig fattening diet on

performance (exp. CCM2; n= 3 per treatment)

% CCM inclusion

0 20 40 SEM P

Average daily feed intake (g/day) 2709 2911 2803 41 0.117

Average daily feed intake (g dry matter/day) 2384 2426 2187 42 0.023

Average daily gain (g/day) 974 968 892 15 0.018

Feed conversion ratio (g/g) 2.78 3.01 3.14 0.04 0.004

Feed conversion ratio (dry matter basis, g/g) 2.45 2.50 2.45 0.02 0.596

IV.A.4. DISCUSSION

The two experiments were conducted to make an evaluation of the use of CCM separate from

potential matrix or nutrient effects. Indeed, inclusion of CCM in exp. CCM1did not lead to a

change in other ingredients. However, it led to a lower protein to energy ratio and lower

concentrations of the vitamin and mineral premix on higher CCM inclusion rates. These

factors were kept constant in exp. CCM2, with consequently some changes in ingredient

composition of the different concentrates. Therefore, while exp. CCM2 had more practical

relevance, exp. CCM1 was necessary to exclude that potential differences are due to other

ingredients that were changed by feed formulation.

Feed analyses did not reveal major deviations, except for the crude fibre in the 0% feed

during the second experiment. The latter may be due to deviations of some ingredients from

their corresponding matrix values.

In both experiments, the CCM inclusion level had no effect on the measured meat and carcass

quality traits. Carcass and meat quality were fairly good and comparable to common practice.

Therefore, inclusion of CCM up to a level of 40% did not endanger meat or carcass quality.

The observed effect of gender on meat percentage is well known (Thomke et al., 1995;

Youssao et al., 2002). Sundrum et al. (2000) demonstrated that the lack of a well balanced

amino acid profile in organic farming may influence carcass quality. However, in the present

experiment, even in the “unbalanced” 40% CCM group of exp. CCM1, the minimal ileal

digestible lysine concentrations could be attained, leading to an acceptable carcass

conformation.

The NE-value derived from equation (1) matched rather well with the table value of 7.2

MJ/kg (published by DSM nutritional products, Deinze, Belgium).

119

The assumption of an equal feed energy conversion ratio is not an exact, but rather a useful

economical approximation, as in field practices the feed conversion ratio together with the

lean meat percentage will largely determine the price per kg of meat.

Exp. CCM2 confirmed the assumption of an equal feed energy conversion ratio. Indeed, on an

equal dry matter basis, the FCR did not differ between the treatment groups.

On a dry mater basis, the energy concentration of CCM is somewhat higher than the

concentrate (10.2 vs 8.9), leading to energy concentrations on a dry matter basis of 8.9, 9.1

and 9.3 for the 100:0, 80:20 and 60:40 groups, respectively. Therefore, differences in energy

concentrations were relatively small (5% between the 100:0 and the 60: 40 group). This might

explain the lack of significant differences in FCR on a dry matter basis.

As CCM has a lower dry matter content, the dilution effect was expected to alter feed intake.

Whittemore et al. (2001) confirmed the framework that pigs eat to achieve maximum

performance, unless they are constraint, in this case by the bulk content of the feed. Henry

(1985) concluded from literature data that a decrease in energy density is associated with a

compensatory increase in daily feed intake, although to a lesser extent, leading to a slightly

lower level of energy consumption. Therefore, in these experiments, although the CCM has

no excessive crude fibre content, the dilution effect of the water was expected to limit the dry

matter intake and lower the energy intake.

In the two experiments average daily feed intake varied with CCM inclusion. In exp. CCM1,

the pigs tended to compensate the dilution effect of adding CCM by a higher feed intake.

Indeed, differences in dry matter intake could not be found. In exp. CCM2 however, the pigs

already showed a high (higher than in exp. CCM1) feed intake when given concentrate.

Therefore, the dilution effect of CCM did not lead to a remarkably higher feed intake on an

“as fed” basis, and even a lower dry matter intake of the 40% group was noticed. Therefore, a

bulk effect was noticed in exp. CCM2, but not in exp. CCM1. Moreover, this bulk effect was

not considered favourably in these experiments, as the meat percentage of the pigs on the

concentrates was fairly good. As a result, the use of CCM to limit the feed intake is only

beneficial in cases of excessive feed intake typically seen in certain combinations of breeds

and housing types, leading to fatter carcasses.

A breed effect was demonstrated by Sellier et al. (1974) and Pekas et al. (1983), who showed

an interaction between genotype and diet type on carcass quality.

The changes in daily energy intake when adding a semi-moist product seems to depend on the

spontaneous feed intake of concentrate and therefore a bulk effect of CCM can be present in

some, but not all cases.

120

The lower dry matter content of the CCM affected the FCR on an as fed basis. Indeed, the

effects of a higher FCR on higher inclusion rates of CCM can be explained by the dilution

effect of the moisture, leading to diets with a lower energy content. As the CCM had a lower

NE value on an as fed basis, higher inclusion rates lead to a worse FCR in both experiments.

Nonetheless, the present trials demonstrate that CCM can be used without deteriorating meat

percentage and dry matter feed conversion ratio.

The lower cost of CCM in comparison to concentrates would be helpful in lowering the feed

cost, which is quite high in organic pig fattening (Sundrum et al., 2000a). However, because

the use of synthetic amino acids in organic farming is currently prohibited and because this

CCM has a low and unbalanced protein content, the inclusion of CCM will be limited by

nutritional demands. In these experiments, an inclusion rate of CCM up to 40% could be

formulated within strict amino acid requirements.

Based on the lower feed cost and given that meat percentage and feed conversion ratio were

not affected, the use of CCM in these experiments was considered favourable from an

economical point of view. This can alleviate the high feed cost of organic feeds. The major

hurdle might be the low protein content of the CCM.

IV.A.5. CONCLUSION

CCM is a homegrown feed ingredient that can be used in (organic) pig fattening. Lean

carcasses with good meat quality can be obtained even in situations where up to 40% organic

CCM-silage is included in a balanced organic pig fattening diet.

Changes in feed intake and feed conversion ratio may be attributed to the lower dry matter

content of CCM. A bulk-effect can occur in some cases. The use of CCM in organic pig

nutrition is considered favourable from an economical point of view. However, the major

hurdle will be the lack of a well-balanced protein content.

121

IV.B. EFFECT OF CCM INCLUSION ON IMMUNOCOMPETENCE IN

ORGANICALLY FED FINISHING PIGS

ABSTRACT

Two consecutive experiments were performed to evaluate the effects of corn cob mix (CCM)

in an organic pig diet on the immune responsiveness. The IgM, IgA and IgG response against

an intramuscularly injected model antigen, bovine thyroglobulin, was used as an indicator.

The experiments were performed in an organic barn with 9 pens of 4 crossbred pigs (2

barrows and 2 sows) from 45 kg to slaughter. In the first experiment (exp. CCM1), the

organic concentrate was mixed with organic CCM-silage to obtain three concentrate:CCM

ratios of 100:0, 80:20 and 60:40 (w:w). In the second experiment (exp. CCM2), three

concentrates were produced to obtain diets with equal nutrient levels on a dry matter basis

after 0%, 20% and 40% CCM inclusion, respectively. Higher inclusion rates of CCM in the

ration were accompanied with lower thyroglobulin-specific IgG responses. These effects

could not be attributed to one specific component of the CCM such as fatty acid composition,

although there was a degree of correlation with lower vitamin A concentrations. Moreover,

mycotoxin concentrations were absent or minimal. In conclusion, this study indicates that the

dietary ingredient composition may affect immunocompetence, independent of parameters

that are taken into account in feed formulation.

Keywords: Corn Cob Mix, Feed composition, Immunocompetence, Organic farming, Pigs.

After:

S. Millet, E. Cox, M. Van paemel, K. Raes, M. Lobeau, S. De Saeger, S. De Smet, B. M.

Goddeeris, G.P.J. Janssens. Immunocompetence in organically fed finishing pigs: effect

of CCM inclusion, submitted.

122

IV.B.1. INTRODUCTION

In organic pig fattening, legislation prescribes that prevention of disease must be through

selection of an appropriate breed, appropriate housing and management and nutrition (Council

of the European Union, 1999). Previous research revealed that the subtle differences between

a conventional and an organic diet did not exert important effects on immunocompetence of

fattening pigs (chapter III.2). However, the use of certain feedstuffs may be either

advantageous or unfavourable for the development of immune status of fattening pigs: several

macro- and micro-elements were shown to affect immune status (Cunningham-Rundles,

2002). Corn is known to be a source of carotenoids with precursor activity for vitamin A

(Egesel et al., 2003). As carotenoids may influence immunocompetence (Hughes, 2002), the

effect of corn cob mix (CCM) in an organic finishing pig ration on immune responsiveness

against a novel antigen was evaluated in two consecutive experiments.

IV.B.2. MATERIAL AND METHODS

IV.B.2.1. Animals and management

In each experiment, a group of 36 pigs was used. The genotype was a crossbreed of a

(Yorkshire×DL) sow and a Piétrain boar in experiment 1 and a terminal crossbreed of a

paternal line and a maternal 3-way crossbreed of Seghers Hybrid (currently Rattlerow

Seghers) in experiment 2. The pigs were randomly divided over 9 pens of 4 pigs in an organic

production unit (2 barrows and 2 sows per pen).

The pigs were kept according to conventional husbandry practices until weaning. One week

after weaning they were moved to the organic barn at the experimental production site and

grown according to organic production rules.

Each group of 4 pigs had access to an outdoor area of 8 m² with a concrete floor and an indoor

area of 8 m² with straw bedding. The barn was naturally ventilated and straw was replaced

twice a week. Housing was in accordance with the EC-regulations on organic production

(Council of the European Union, 1999). One self-feeder (four feeder holes) and one nipple

waterer were provided in each pen. Environmental temperature was recorded with electronic

devices every hour (Testostor, Testo Ltd., Almere, The Netherlands).

All pigs received the same organic starter diet (9.5 MJ NEv, 9 g ileal digestible (ID)

lysine/kg) from weaning until 20 kg BW, and growing diet (9.6 MJ NEv, 8 g ID lysine/kg)

from 20 to 45 kg BW. At an average BW of 44 ± 5 kg (about 15 weeks of age), the

123

experiment started. At that moment, all pigs were dewormed (Ivomec®, Merial) and

vaccinated against Aujeszky’s disease.

Each pen was randomly assigned to one of three dietary treatments (description of diets: see

below).

IV.B.2.2. Feed composition

IV.B.2.2.1. Experiment CCM1

Per treatment, one feed was used from 45 to 105 kg BW. An organic concentrate was mixed

with organic CCM-silage to obtain three concentrate:CCM ratios of 100:0, 80:20 and 60:40

(w:w). Relying on the amino acid requirements obtained in earlier research (chapter II), the

concentrate was formulated in a way that excluded amino acid deficiencies, even in the 40%

group (table IV.1, chapter IV.A). Nutrient content of the three experimental diets on an 88%

dry matter basis is given in table IV.7. The feed was formulated in accordance with EC

guidelines on organic production (Council of the European Union, 1999)

The CCM was produced according to organic legislation (Council of the European Union,

1991) and ensiled with plastic seal. For the appropriate use of small amounts of CCM, it was

re-ensiled in barrels of approximately 170 kg. The concentrate was produced by Molens

Dedobbeleer (Halle, Belgium) and was subject to proximate analysis (AOAC, 1980).

IV.B.2.2.2. Experiment CCM2

Per treatment, one feed was used from 45 to 105 kg BW. Three concentrates (A, B and C)

were produced to obtain diets with similar nutrient demands on a dry matter basis when

respectively 0, 200 or 400 g/kg CCM was included in the total diet on an as fed basis (table

IV.2, chapter IV.A). Therefore, on a dry matter basis, 0%, 15.2% and 32.3% CCM was

included [100 × (20 × 0.63)/(80 × 0.88 + 20 × 0.63)= 15.2 and 100 × (40 × 0.63)/(60 × 0.88 +

40 × 0.63)= 32.3]. The feed was formulated in accordance with EC guidelines on organic

production (Council of the European Union, 1999)

The CCM used in this experiment was the same as the CCM used in the exp. CCM1.

Concentrates were produced by Molens Dedobbeleer (Halle, Belgium) and were subject to

proximate analysis (AOAC, 1980).

124

Table IV.7 Nutrient content of the three experimental diets in exp. CCM1 expressed on an 88% dry

matter basis

concentrate:CCM ratio (w:w)

100:0 80:20 60:40

NEv’97A (MJ/kg) 8.9 9.1 9.3

Dry matter (g/kg) 880 880 880

Crude ash (g/kg) 68 60 51

Crude fibre (g/kg) 60 57 53

Crude protein (g/kg) 222 201 178

Ether-extract (g/kg) 43 42 41

ID LYSB 9.1 7.9 6.6

ID MET+CYS / ID LYSB 0.58 0.59 0.59

ID THR/ ID LYSB 0.64 0.65 0.65

ID TRP/ ID LYSB 0.22 0.22 0.22 ANEv’97= net energy for production in pigs according to the Dutch CVB system 1998 BID MET= ileal digestible methionine, ID MET+CYS= ileal digestible methionine and cysteine, ID THR= ileal digestible threonine, ID TRP= ileal digestible tryptophan and ID LYS= ileal digestible lysine

IV.B.2.3. Measurements

IV.B.2.3.1. Feed compounds

Pro-vitamin A carotenoids and vitamin A were measured by HPLC as they can influence

immune responsiveness.

To exclude effects of mycotoxins on immune function, zearalenone (ZEA), aflatoxin B1

(AFB1) and ochratoxin A (OTA) concentrations were determined by HPLC with fluorescence

detection (De Saeger et al., 2003) in both the experimental concentrates and the CCM.

Deoxynivalenol (DON), fumonisin B1 (FB1), fumonisin B2 (FB2) and fumonisin B3 (FB3)

were quantified by using liquid chromatography-positive electrospray ionisation-mass

spectrometry (LC-ESI-MS/MS) using multiple reaction monitoring (not published). For all

mycotoxins sample clean-up was done by immunoaffinity columns (Vicam, Watertown, MA,

USA). Detection thresholds were 25, 5, 2, 4, 57, 21 and 125 µg/kg for ZEA, AFB1, OTA,

DON, FB1, FB2 and FB3 analysis, respectively. As fatty acid composition may play an

important role in immune function, fatty acids in concentrates and CCM were determined

using gas chromatography (Raes et al., 2001) preceded by a chloroform/methanol extraction

adapted from Folch et al. (1957).

125

IV.B.2.3.2 Immunological measurements

One week after the onset of CCM feeding, all pigs were injected i.m. with 1 ml of an

emulsion of equal volumes of PBS containing 1 mg bovine thyroglobulin T-1001 (Sigma) and

incomplete Freund’s adjuvant. A second identical injection was given three weeks later.

Blood samples were drawn from the jugular vein before the first thyroglobulin injection, and

3 and 7 weeks post immunisation. A final sample was collected at slaughter. After overnight

incubation at room temperature, serum was separated and stored at -18°C until analysis.

Analysis of thyroglobulin-specific antibodies was performed as described in chapter III.B.

IV.B.2.4. Statistical analysis

The kinetics of the thyroglobulin-specific antibody response was analysed using a General

Linear Model (Repeated Measures Analysis of variance, SPSS 11.0.1 for Windows). The

model included the fixed effects of % CCM and gender and their interaction.

IV.B.3. RESULTS

Average indoor and outdoor temperature during the experiment CCM1 were 20 ± 4°C and 17

± 6°C respectively. Average indoor and outdoor temperature during the experiment CCM2

were 16 ± 4°C and 12 ± 5°C respectively.

Results of the feed analyses on n-3/n-6 fatty acid composition, mycotoxin content and vitamin

A and β-carotene content are presented in tables IV.8, IV.9 and IV.10. Inclusion of CCM in

the experiment CCM1 led to a lower concentration of alfa linolenic acid (ALA) and vitamin A

in the diet. In the experiment CCM2, higher CCM inclusion did not lead to changed ALA

levels. Vitamin A was in this experiment also lower in diets with higher CCM inclusion.

Table IV.8 Concentration of linoleic acid, linolenic acid and n-3/n-6 fatty acid composition of the

experimental diets (mg/100g feed)

Experiment CCM1 Experiment CCM2

100:0 80:20 60:40 0% 20% 40%

C18:2n-6 1283 1356 1429 1571 1469 1698

C18:3n-3 353 288 222 458 460 529

C 18:3n-3/ C 18:2n-6 0.27 0.21 0.16 0.29 0.31 0.31

126

Table IV.9 Mycotoxin concentration in the experimental diets (µg/kg)

Concentrate Concentrates second experiment

CCM first experiment Aa Ba Ca

Zearalenone < 25 < 25 < 25 < 25 < 25

Aflatoxin B1 < 5 < 5 < 5 < 5 < 5

Ochratoxin A < 2 < 2 < 2 < 2 < 2

Deoxynivalenol 21.0 7.3 7.5 6.9 7.0

Fumonisin B1 <57 - <57 <57 <57

Fumonisin B2 <21 - <21 <21 <21

Fumonisin B3 <125 - <125 <125 <125 a concentrate A: as fed; concentrate B: to be mixed with CCM in a concentrate CCM ratio of 80:20; concentrate C: to be mixed with CCM in a concentrate CCM ratio of 60:40

Table IV.10 Concentrations of β-carotene and vit A measured in the experimental feeds as fed in

experiment CCM1 and CCM2

Experiment CCM1 Experiment CCM2

100:0 80:20 60:40 0% 20% 40%

β-carotene (mg/kg) <0.1 <0.1 <0.1 2.1 1.16 0.7

vitA (IU/kg) 9610 7688 5766 11200 6616 5000

The concentrate:CCM ratio influenced neither the IgA response during exp. CCM1 (P=

0.148) or exp. CCM2 (P= 0.231) nor the IgM response during exp. CCM1 (P= 0.662) or exp.

CCM2 (P= 0.716) (figures IV.1 and IV.2). Adding CCM to the diet clearly affected kinetics

of the IgG both exp. CCM1 (P= 0.005) and exp. CCM2 (P= 0.034). The pigs on the 60:40

ratio showed significantly lower IgG values 4 (P= 0.009) and 7 (P= 0.004) weeks after the

start of experiment CCM1, and at slaughter (P= 0.007) (figure IV.1). With the balanced feeds

in experiment CCM2, a tendency (P= 0.091) to lower IgG values with higher inclusion of

CCM was noticed 4 weeks after the start of the study. Seven weeks after the start (P= 0.002)

and at slaughter (P= 0.035), the 40% CCM group showed significantly lower IgG values than

the 0% group. The 80% group was intermediate (figure IV.2).

127

IGG

aa

a

a

aa

a

a

bb

ba

00,20,40,60,8

11,21,41,6

1 week 4 weeks 7 weeks slaughter

OD

(1/1

5)

IGA

00,050,1

0,150,2

0,25

1 week 4 weeks 7 weeks slaughter

OD

(1/1

5)

IGM

0

0,2

0,4

0,6

0,8

1 week 4 weeks 7 weeks slaughter

OD

(1/1

5)

00,050,1

0,150,2

0,25

1 wee

k

4 wee

ks

7 wee

ks

slaug

hter

0% CCM 20% CCM 40% CCM

Figure IV.1 The influence of the concentrate:CCM ratio (100:0, 80:20 or 60:40) on thyroglobulin-specific

IgG, IgA, and IgM antibody response in exp. CCM1 (mean ± SE).

Pigs were injected with bovine thyroglobulin 1 week and 4 weeks after the start of CCM inclusion in the

diet. a,b different indices mean significant differences by Scheffé’s post hoc test.

IGG

aa

a

a

ab aba

a

bba

a0

0,20,40,60,8

11,2

1 week 4 weeks 7 weeks slaughter

OD

( 1/

15)

IGA

0

0,05

0,1

0,15

0,2

1 week 4 weeks 7 weeks slaughter

OD

(1/1

5)

IGM

00,050,1

0,150,2

0,25

1 week 4 weeks 7 weeks slaughter

OD

(1/1

5)

0

0,05

0,1

0,15

0,2

0,25

0% CCM 20% CCM 40% CCM

Figure IV.2 The influence of 0, 20 or 40% CCM inclusion in the diet formulation on thyroglobulin-specific

IgG, IgA, and IgM antibody response in exp. CCM2 (mean ± SE). Pigs were injected with bovine

thyroglobulin 1 week and 4 weeks after the start of CCM inclusion in the diet.

a,b different indices mean significant differences by Scheffé’s post hoc test.

128

IV.B.4. DISCUSSION

In both experiments, an increasing level of CCM in the diet lowered IgG response.

In experiment CCM1, adding CCM to the diet led to lower protein content. Similarly, the

concentration of the mineral and vitamin premix diminished with addition of CCM. Although

the feed was formulated in a way that excluded deficiencies even in the group with 40%

CCM, relying on the first experiment, the difference in IgG response could be attributed to

differences in protein, vitamin or mineral content between the three diets. In experiment

CCM2 however, the protein:energy ratio was equal between the diets, and the mineral and

vitamin premix was held constant (table IV.2). Therefore, attributing the effects to differences

in formulated nutrients (energy, amino acids) or premix concentration, which could be

hypothesized from experiment CCM1, cannot be sustained by the results of experiment

CCM2: if this was the case, experiment CCM2 would not have shown similar effects.

Several mycotoxins may be found in corn (Fazekas et al., 1996). Mycotoxins may affect

humoral immunity (Bondy and Pestka, 2000; Oswald and Comera, 1998). Feeding diets that

were contaminated with 2000 µg/kg DON and 157 µg/kg zearalenone, increased IgA and

decreased IgG serum concentration in growing pigs (Pinton et al., 2004). Others found

increased IgA serum concentrations without changes in serum IgG concentration (Swamy et

al., 2002). Therefore, one must assure that feedstuffs are not contaminated with mycotoxins.

In the present experiments, the mycotoxin concentrations were absent or minimal, and may

therefore not be held responsible for the observed immunological effects.

As corn is known to be a source of carotenoids, which may have a pro-vitamin A activity,

effects of CCM inclusion in a diet was expected to alter the immune response. In vitro

experiments in mice indicated that vitamin A inhibits secretion of Th1 cytokines but not Th2

cytokines (Frankenburg et al., 1998). In 1963 already, Harmon et al. (1963) detected that

vitamin A deficient pigs in comparison to vitamin A fortified pigs show a lower antibody

response against an intramuscularly injected antigen, phenolised Salmonella pullorum.

However, analyses of the experimental diets revealed that, although CCM is a source of pro-

vitamin A carotenoids, the concentrate feeds exceeded the levels of carotenoids (exp. CCM2)

and vitamin A (exp. CCM1 and CCM2). This is probably due to the addition of a vitamin and

mineral premix to the concentrate diets. Moreover, table IV.2 shows that increasing inclusion

of CCM was accompanied by a lower corn concentration in the concentrates. Therefore, in

balanced feeds without CCM inclusion (0% group in exp CCM2), the corn will provide

carotenoids. In addition, the breakdown of carotenoids during storage has to be taken into

129

account. In the present experiments, the analysed vitamin A and β-carotene concentrations

were even lower with higher inclusion rates of CCM. These lower concentrations may

indicate a correlation between the vitamin A and β-carotene content in the diet and

thyroglobulin-specific IgG response, although it is unlikely that any pig was deficient in

vitamin A. Therefore, the lower vitamin A concentration may partly explain, but not for sure,

the altered IgG response.

Other nutrients with a proven impact on immune function are fatty acids. Supplementation of

α-linolenic acid elevated the IgG concentration in serum of laying hens (Wang et al., 2000).

As the CCM had a low n-3 fatty acid concentration, adding CCM to a concentrate lowered the

n-3:n-6 ratio. However, analysis revealed that the concentrates B and C (to be mixed with

respectively 20 and 40% CCM) during exp. CCM2 showed higher n-3 fatty acid

concentrations, leading to similar levels in the three experimental feeds during exp. CCM2.

Therefore, attributing the observed effects to differences in fatty acid composition could be

suggested from the experiment CCM1, but cannot be sustained through experiment CCM2.

So, although some hypotheses might explain partly the observed differences in exp. CCM1 or

exp. CCM2, the lower IgG response cannot be attributed to one specific element in the diet.

IV.B.5. CONCLUSION

Inclusion of CCM in an organic finishing pig nutrition affected thyroglobulin-specific

antibody responses in these experiments, indicating that inclusion of alternative feedstuffs in a

diet may affect immunocompetence. This may be due to nutrient demands that were not taken

into account in common feed formulation.

130

131

CHAPTER V. GENERAL DISCUSSION

MAIN RESULTS

In the first part of this thesis, growth performance, product quality, immunocompetence and

some metabolic characteristics in an organic pig fattening unit were compared with the

conventional counterpart.

Nutrient requirements, growth and product quality

In Chapter II, the protein requirement in an organic barn was examined. As the feeds were

formulated with lysine as the first limiting amino acid, the ileal digestible lysine content of the

feeds was compared. The fixed ratio of digestible lysine to protein matched with organic

nutrition practice, because there is a ban on synthetic amino acids. This implies that protein-

rich ingredients will have to be included in a diet to raise the levels of individual amino acids.

Based on the findings of the first phase of growth (± 20-45 kg), a higher digestible lysine

concentration in the diet led to improved performance. Feed conversion ratio was linearly

related to dietary digestible lysine concentration in this phase of growth. As a result, higher

levels of digestible lysine than those used in this study might have led to better performance.

Although the High Protein (HP) feed had a lysine level that is also found in conventional pig

fattening, we cannot say for certain that an optimal level was reached. Therefore, a lower

protein concentration in this phase of growth is not sustainable with regard to pig

performance.

The above-mentioned findings were confirmed in the second experiment: A better feed

conversion ratio between 20 and 40 kg was observed on the conventional diet, which could be

attributed to a higher digestible lysine content of this diet.

From 40 kg on, the Medium Protein (MP) feed could be applied. This was a feed with a lower

protein concentration in comparison to the HP feed. The HP feed had a digestible lysine level

in conformity with feeds used in conventional pig fattening. However, published amino acid

requirements are diverse (National Research Council, 1998) and published total lysine

requirements for pigs between 40 and 100 kg live weight ranged between 6.0 and 11.7 g/kg.

Still, these numbers should be considered with caution. Differences in published requirements

might be due to line differences or variation in environmental conditions, energy

132

concentration of the diets and level of feed intake. Moreover, instead of total lysine content,

digestible lysine content of a diet is a more accurate tool in composing a diet.

Nevertheless, the pigs seemed to have the ability to correct for lower protein levels by feed

intake. Subsequently, they corrected small amino acid deficiencies by extra feed consumption.

Indeed, the pigs on the low protein feed had a similar daily digestible lysine intake compared

with the MP-group. Yet, these observations were made in a production system that was

characterised by a high feed intake. In housing systems with a lower feed intake, factors other

than nutrient requirements might limit the appetite of the pigs. Moreover, compensation for a

low amino acid content through an increased feed intake may not be beneficial, as it will lead

to a greater energy intake, and a lower meat percentage of the carcass when the level of

maximal protein deposition is exceeded. That assumption was supported by the results from

this experiment.

Fattening of pigs in the organic housing system was characterised by a large feed intake. The

higher feed intake cannot solely be attributed to a compensation for the hypothesized larger

maintenance energy demands, because this would have led to a slightly higher feed intake, an

equal growth and consequently a worse feed conversion ratio. In contrast, the feed conversion

ratio did not differ significantly between the housing types, resulting in a higher daily gain in

the organically housed pigs.

Nevertheless, the higher feed intake in the organic barn is not always beneficial. If the

maximal protein deposition rate is attained, extra feed consumption will not lead to additive

protein deposition. Instead, the extra daily energy intake might lead to an extra amount of fat

deposition, which is detrimental for the carcass composition, as was the case in the third

experiment (table V.1).

Table V.1 shows a consistently higher feed intake in the organic barn, with a highly variable

meat percentage between experiments.

Other factors, like the genetic background of the pigs will affect growth rate and carcass

quality. Pigs with a high maximal protein deposition rate might be selected, which may lead

to optimal carcass conformation. This is an important conclusion and demonstrates the

difference between organic agriculture on the one hand, that aims to be a modern sustainable

agriculture, incorporating recent knowledge and breeds, and a traditional, extensive way of

pig holding on the other. Based on the findings when feed intake was high, an excessive

energy intake should be minimized. This might be possible by restricted feeding or by feeding

low energy bulk feeds. Restricted feeding is less advisable, especially in organic farming,

because it might affect animal welfare. Therefore, the use of bulk feeds for fattening pigs

133

should be evaluated. In this thesis, the use of CCM as a semi-moist product was evaluated. It

was shown that a bulk effect can be present.

Table V.1 Average daily gain in the different experiments from 20 kg until slaughtering and the

corresponding meat percentages

Average daily growth (g/day) Lean meat percentage (%)

Breed Organic Conventional Organic Conventional

Exp 1 Terminal crossbreed of a paternal line and a maternal cross of Seghers hybrid (Nn)

797 ± 38 57±5

Exp 2 Piétrain boar x (Belgian Landrace x Duroc) sow 758 ± 54 648 ± 37 56 ± 4 56 ± 5

Exp 3 Terminal crossbreed of a paternal line and maternal cross of Seghers hybrid (NN)

850 ± 40 732 ± 27 52 ± 4 57 ± 5

Exp 4 Piétrain boar x (YorkxDL) sow 829 ± 36 59 ± 5

Exp 5 Terminal crossbreed of paternal line and maternal cross of Rattlerow Seghers (Nn)

868 ± 38 61 ± 3

Differences between organic and conventional housing and nutrition on meat quality

characteristics were not consistent between chapter III.A.1 and III.A.2. It is likely that

genotype or rearing environment exerted an effect on the results. In the second experiment,

the piglets originated from an organic pig-breeding unit, whereas in the third experiment, a

commercial breed from the experimental farm was used. The way pigs are reared from birth

until weaning can be important as well. According to Belgian legislation on pig breeding in

organic agriculture, pigs are born and reared outdoors. Higher activity from these pigs can

therefore be assumed. This in turn can affect meat characteristics, like fibre type distribution.

Indeed, Gentry et al. (2004) revealed a higher percentage of type I fibres in pigs that were

reared outdoors from birth until weaning. Because the pigs in the third experiment were all

reared conventionally from birth to weaning, some of the system-specific measures might

have been missed. However, this experimental design was preferred as genetics are very

important for meat quality (Renand et al., 2003).

Meat quality measurements did not reveal aberrant values, and were fairly good in most pigs

for the different experiments. In reality, differences in meat quality characteristics may be

134

attributed to more fundamental differences, like higher slaughter weights, genetics or diet

composition.

Ngapo et al. (2004b) state that for consumers, colour and fat cover are the most important

characteristics when buying pork chops. However, half of the consumers preferred dark meat

and the other half light meat (Ngapo et al.,2004; Verbeke et al., 2005) The majority of

consumers preferred lean meat. In addition, the leanness of the carcass determines the price of

the carcasses and is therefore of major concern. Other factors may be less important in

determining consumers’ preferences, as long as they do not show aberrant values. Because no

abnormal values were found in the above-mentioned experiments, organic pig fattening can

be practiced without loss in quality. Nevertheless, consumers believe that extensive rearing

(and probably also organic farming) gives better meat quality (Ngapo et al., 2004a), which

however cannot be concluded from the presented studies. In addition, consumer demands on

meat characteristics might be altered by their perception of the production system, although

scientific data to support this statement could not be found.

Thyrogobulin, lactate and acute phase proteins

The accidental Actinobacillus pleuropneumoniae infection interfered with the immunological

measurements in experiment 2 and those results were not taken into account. In the third

experiment, the housing type induced slight differences in thyroglobulin-specific antibody

responses. However, in this experiment, potential effects of rearing were not included.

Organic pigs are weaned at 7 weeks, 3 weeks later compared with conventional practices and

this might affect immune status.

At slaughter, higher lactate values were measured in the stabbing blood of animals from the

conventional barn, together with higher haptoglobin levels. This suggested a higher capability

of the pigs from the organic housing system to cope with the stressful circumstances of

slaughtering. As mentioned before in the literature review, an organic production system

cannot be considered as a stress-free housing system. In contrast, the pigs in this system

experience more stimuli, like cold stress and the larger space allowance, which may stimulate

them to move around. This could explain their increased ability to cope with stressful

circumstances at slaughter or the physical stress due to load, transport and discharge.

Although we expected this to be beneficial for meat quality characteristics, this was not

observed in the experiments.

Potential subtle differences between organically and conventionally produced feedstuffs did

not affect the measured parameters on immunocompetence.

135

The use of CCM in an organic pig fattening barn

The use of different ingredients can influence immune responsiveness against a new antigen.

This was supported by the results from the studies on CCM. The inclusion of CCM in the diet

had a clear effect on thyroglobulin-specific IgG response to intramuscularly injected

thyroglobulin. Higher inclusion rates led to a lower antibody responses in two experiments.

Although the use of CCM led to changes in nutrients, e.g. vitamin content, none of these

changes could explain the observed effects entirely.

Corn cob mix was tested as a feed with lower dry matter content. Moreover, it can be

produced extensively in Belgium and it is therefore a good example of a product from local

origin. From the two experiments with CCM we concluded that inclusion of CCM up to a

level of 40% does not negatively affect performance or meat quality. Corn cob mix promotes

sustainability because of its local origin. The use of this product will also lower the feeding

cost, which makes it a useful feed ingredient today.

However, advantages of the low dry matter content were limited. In one experiment (chapter

IV.A), a slight bulk effect was observed. This led to a slower growth in the 40% CCM group

but did not affect lean meat percentage. Therefore, the use of CCM with the purpose of

limiting the energy intake might only be beneficial in pigs with a limited protein deposition

capacity. Moreover, it is a feedstuff with low protein content and the concentrate in which it

has to be mixed will have to be rich in protein.

Ideally, feedstuffs should be low in energy with sufficient amino acid supply. This should

enhance the sustainability of the production system in comparison with locally grown energy-

rich ingredients. The latter have to be supplemented with protein sources that have been

produced overseas, necessitating the import of nutrients and the use of fossil energy for

transport. An additional disadvantage of CCM and more in general corn, is the difficulty to

include it in crop rotation systems, as it competes with vegetables for human use.

EXPERIMENTAL DESIGN IN ORGANIC LIVESTOCK RESEARCH

The use of a “semi-holistic” design

Organic pig fattening represents an entire production system, which differs from conventional

pig fattening in several ways. Differences between an organic and a conventional system can

hardly attribute to one or another element. Therefore, the second and third experiment can be

perceived as semi-holistic, the organic and the conventional barn each representing a

136

production system, with special emphasis on feeding type. As the organic and the

conventional feed differed in several aspects, it is impossible to attribute possible effects to

just one element. However, this method of approach is justified for several reasons:

• Differences found between production systems, although not unambiguously

attributed to one or another element, may be relevant and easily applied in real

farm conditions.

• As numerous elements are inherent to a system, all these elements have to be

included when comparing production systems.

• Specific elements that raise questions can be kept constant in a further stage, to

elucidate their specific action within a system.

• One should be very careful in extrapolating findings of a reductionistic design to

practice, as this might lead to wrong conclusions in some cases. In the present

study for example, the organic housing led to a remarkable increase in average

daily feed intake. However, when the effects of housing would have been studied

in a reductionistic experimental design, with for example a treadmill to standardise

activity and climate control to vary temperatures, it is not certain that a similar

excessive increase in feed intake would have been noticed.

ORGANIC AGRICULTURE - THE FUTURE ?

Based on the results of these experiments, organic pig fattening is technically feasible without

losses in technical performance. However, labour intensity and high feed costs compromise

the economic sustainability of this sytem. Organic pig production is and will most likely

remain a niche market. The growth of the organic market will depend on the consumer’s

willingness to pay. In The Netherlands, animal welfare and food safety are of major concern

to consumers, but they do not want to buy pork with certain assurances if the price increase is

more than 50% (Meuwissen and van der Lans, 2004).

Organic agriculture aims to be a sustainable agriculture. It is a production system that tries to

achieve this sustainability by a strict legal framework. Still, some bottlenecks have to be

solved regarding feeding practices. In organic pig fattening, major concerns are that:

• the limited choice of ingredients makes it difficult to formulate a 100% organic

feed, matching all amino acid requirements;

• this implies an import of organic feedstuffs produced overseas, which involves the

use of fossil energy for transport;

137

• high-quality feedstuffs for human use have to be included to produce a balanced

organic pig feed.

These problems endanger the sustainability of organic pig production. Another issue is the

ban on synthetic amino acids. The use of synthetic amino acids would lower the need for

protein rich feedstuffs and could enhance the utilisation of locally grown feedstuffs of 100%

organic origin.

However, the strict rules on organic farming results in an innovative production method that

counters specific problems. Solutions to these problems will enhance sustainability, and can

be used in organic as well as in conventional farming.. Therefore, although conventional

farmers often perceive organic agriculture in a negative way, this form of production might be

able to solve problems from which the entire agricultural system can benefit. For example, the

high costs of the feedstuffs and the principles of organic agriculture urge the search for home-

grown protein sources, which could also be used in conventional agriculture. In our research,

it was shown that – apart from the intrinsic costs for organic feed, labour and lower housing

density – a more extensive way of farming is possible without performance and production

losses. This suggests that alternative housing systems, taking into account the welfare of pigs,

may be obtained in a way that avoids supplementary economic losses.

RECOMMENDATIONS FOR FUTURE RESEARCH

From a nutritional point of view, future research should include an exploration of new,

alternative feedstuffs. Initially, feedstuffs from local origin and by-products will have to be

evaluated as organic feed ingredients for their nutritive value and their applicability. As

previously mentioned, feedstuffs enhancing the protein content of a cereal-based diet may be

perceived positively. Moreover, feedstuffs for animal feeds must not compete with products

for human use.

As the use of allopathic medicines has to be restricted, management and especially proper

nutritional strategies will play an even greater part in organic pig production than in

conventional pig production. Nutritional strategies to enhance performance and lower disease

susceptibility form a challenge to researchers, which might be useful in organic as well as in

conventional pig production systems.

Moreover, the sustainability of the system has to be evaluated more thoroughly. Hence, the

organic pig farming branch should be evaluated as part of the total organic agricultural sector.

Nutrient cycles must include the total system of livestock and plant production. Therefore,

138

nutrient utilisation efficiencies of plants and animals have to be combined, including organic

pig production in the crop rotation. Evidently, this will require a multidisciplinary approach.

139

SUMMARY

Following several problems in the food chain during the 90’s, organic agriculture in Europe

was characterised with a steep climb during the last decade. However, organic agriculture is

still a niche market. Organic livestock production differs at several points from conventional

production and aims to be a type of sustainable agriculture with respect to product quality and

animal behaviour. It is subject to a European and a national legislation that provides strict

production rules.

Major differences in housing are the provision of an outdoor area, a larger space allowance

per animal and a rooting substrate, which is meanly provided as straw.

Major concerns on feeding practices are the ban on synthetic amino acids and the limited

availability of organic ingredients. These make it difficult to create an entire organic well

balanced pig feed. Given the fact that the pigs have a larger space allowance, a higher activity

level was assumed, leading to larger energy expenditure. In addition, in periods of cold and

heat stress, maintenance energy requirements might raise. As protein requirements remain

largely unaffected by these factors, a lower protein to energy ratio was hypothesized in an

organic housing system compared to conventional housing.

In the first experiment, three protein levels were compared. For this, the ileal digestible lysine

level (ID LYS) was changed in isocaloric feeds, with the ID LYS to protein ratio held at a

constant rate. In the first phase of growth (20-40 kg), an optimal protein content was not

found, as higher ID LYS levels led to better performances. In the second and third phase of

growth, a 10% lower protein level, compared to conventional practices was found to be

sufficient. An other interesting finding in this experiment was that pigs on the lowest protein

level showed the same daily protein consumption compared to the medium group. This

suggests that pigs can compensate for small protein deficiencies with a higher feed intake.

This was remarkable, because in all groups a large appetite was noticed.

In two consecutive experiments, the influence of organic versus conventional nutrition was

monitored in either an organic or a conventional housing type.

In two barns, either an organic or a conventional type, half of the pigs received an organic and

the other half a conventional pig feed. Three-phase feeding was applied. Neither of the feeds

contained antibiotic growth promoting agents. Feeds were formulated on an isocaloric basis,

with the ID LYS content of the organic feed being 15% lower than the ID LYS content of the

140

conventional feed. In this way, the organic feed was assumed to meet the nutrient

requirements in an organic barn.

The experiments (exp. 2 and 3) were performed in two consecutive years from February until

July. In exp 2, all pigs originated from the same farm, with consequently the same genetic

background (cross of a Piétrain boar with a (Belgian land race x Duroc) sow). The pigs that

were destined for the organic barn were grown and reared in an organic way (born outdoors,

weaning at 7 weeks of age), whereas the pigs for the organic housing system were born and

reared in a conventional way (born in a farrowing barn, weaning at 4 weeks of age). In exp 3,

all pigs originated from the experimental farm, with a similar genetic background (terminal

crossbred of paternal and maternal lines of Seghers hybrid) but also a similar way of growing

and rearing from birth until weaning. The pigs destined for the organic housing system were

moved to this barn one week after weaning. In this barn, all pigs received the same organic

start diet until the start of the experiment (+/- 20 kg).

The major difference between both housing types, which was consistent over the two

experiments, was the higher feed intake and consequently faster growth of the pigs in the

organic barn. Feed conversion ratio did not differ between housing types. However, this faster

growth led to a higher backfat thickness and consequently lower meat percentages of the

carcasses of organically housed pigs in Exp 3. Experiment 2 did not reveal differences in meat

percentages between housing types, indicating that the higher feed intake was accompanied

by a proportional lean meat deposition. Therefore, maximal capacity for protein deposition

was not attained in the conventional barn in this experiment, in contrast to experiment 3.

Therefore, the choice of breed will also be important in organic farming.

Effects of nutrition on growth and feed conversion rate were limited. Exp 2 revealed a clear

effect of ID LYS content on feed conversion ratio, confirming the findings of exp 1. In exp 3

this was not confirmed. The reason for this is unkown. The second and the third phase of

growth did not reveal influences of either organic or conventional nutrition on feed

conversion ratio.

Feeding or housing type did not consistently affect meat quality. While the second experiment

revealed effects of both nutrition and housing type on meat quality parameters (colour, pH,

intramuscular fat level), this was not confirmed in the third experiment. The major findings

concerning meat quality were the good values of the meat quality measurements in both

experiments. Therefore, it can be stated that high quality pig meat can be attained in organic

pig farming.

141

In experiment 3, specific antibody response against an intramuscularly injected foreign

antigen (bovine thyroglobulin) was measured as a parameter for specific immune response.

For this, bovine thyroglobulin was injected twice with an interval of 3 weeks. Blood was

sampled at regular intervals and serum contents of thyroglobulin-specific IgG, IgA and IgM

were determined. In the serum samples, haptoglobin (an acute phase protein) was measured.

Acute phase proteins are produced in a first line defence mechanism following all kinds of

physical stress. In the slaughterhouse, lactate values were determined in the stabbing blood.

Lactate is formed during physical efforts.

Organic nutrition did not influence these parameters. A slightly higher IgG response was

measured 3 weeks following the first immunisation. Housing type affected the serum

haptoglobin concentration at slaughter. This was accompanied by higher lactate values in the

stabbing blood of conventionally housed pigs, which indicated a higher resistance against the

physical stressors during transport and slaughter procedures in the pigs from the organic

housing system.

In a second part of the experiments, the use of CCM in an organic pig fattening barn was

evaluated. Two experiments were conducted (exp. CCM1 and CCM2) in an organic barn with

36 pigs (9 pens of 4 pigs). Three treatment groups of 3 pens were formed, with 0%, 20% or

40% CCM (on a dry matter base) included in the diet. In exp. CCM1, one concentrate feed

was used, with a protein content that exceeded minimal protein needs even with concentrate:

CCM ratio of 60:40. In experiment CCM2, 3 different concentrate feeds were formulated to

obtain 3 feeds with an equal energy and amino acid composition when respectively 0, 20 or

40% CCM was included. It was concluded that inclusion of CCM up to a level of 40%is

possible without losses in productivity or product quality, although the low protein content

will be the limiting factor in formulating a well-balanced feed. A bulk effect by the lower dry

matter content is possible in some cases. However, inclusion of CCM in the diet led to a

lower thyroglobulin-specific IgG response. Although this was correlated with a lower vitamin

A content in the diet, the effect of CCM on immunocompetence could not be attributed to one

specific element.

Main conclusions of the dissertation are:

• Organic pig fattening can be performed without loss of quality

• Protein to energy ratio in conformity with these of the medium protein feed can be

used in the second and third phase of growth (40-70 and 70-110 kg). This feed had

18% crude protein and 0.65% ID LYS between 40 and 70kg and 16% crude

protein and 0.59% ID LYS between 70 and 110 kg.

142

• Pigs in an organic housing system showed a large appetite that overcompensated

the extra energy cost

• Pigs in the first phase of growth are very sensitive to lysine deficiency,

independent from the production system.

• The type of nutrition (either organic or conventional) does not influence immune

status. For this purpose, specific ingredients will have to be included.

• CCM is a practically useful ingredient in organic finishing pig nutrition

143

SAMENVATTING

Volgend op verschillende voedselcrisissen in de jaren ‘90, kende de biologische landbouw

een sterke groei, hoewel het nog steeds een erg beperkt deel van de totale landbouwsector

inneemt. De biologische veeteelt verschilt op een aantal punten van de gangbare veeteelt en

tracht hiermee een duurzaam systeem te zijn met oog voor productkwaliteit en dierenwelzijn.

Ze is gebonden aan strikte regels binnen een wettelijk kader.

Op het vlak van huisvesting zijn de belangrijkste verschillen de aanwezigheid van een

buitenloop, de grotere ruimte per dier en de aanwezigheid van een substraat om te wroeten,

wat vaak stro is.

Beperkende punten wat betreft voeding zijn het verbod op synthetische aminozuren en het

beperkte aanbod aan biologische ingrediënten. Doordat het erg moeilijk is om een biologisch

voeder te maken dat evenwichtig is, moet op dit moment slechts 80% van de ingrediënten in

varkensvoeders van biologische oorsprong zijn. Voor de overige 20% moet gekozen worden

uit een beperkte lijst gangbare ingrediënten, die vooral eiwitbronnen zijn. Producten van

GGO-oorsprong zijn verboden.

Doordat de dieren een grotere bewegingsruimte hebben wordt verwacht dat de activiteit zou

toenemen, gepaard met een stijgende energetische onderhoudsbehoefte. Doordat de stal niet

wordt verwarmd en enkel mechanisch wordt geventileerd kan worden verwacht dat de

staltemperatuur in bepaalde periodes buiten de thermische comfortzone zal liggen. Hierdoor

zal ook weer de onderhoudsbehoefte stijgen. Aangezien de eiwitbehoefte weinig verandert

door deze factoren, werd de hypothese gesteld dat de eiwit-energieverhouding in een

biologische stal lager zal liggen dan in een gangbaar systeem.

In een eerste experiment werden verschillende eiwitenergieniveaus vergeleken. Hiervoor

werd het gehalte darmverteerbaar lysine (dvLYS) aangepast in isoenergetische voeders, met

een constante verhouding van dvLYS ten opzichte van eiwit. Voor biggen tussen 20 en 40 kg

werd geen optimale dvLYSgehalte gevonden, aangezien hogere gehaltes tot betere prestaties

leidden. In de tweede en derde groeifase (40-70 en 70-105 kg) werd een minimaal

eiwitgehalte gevonden dat 10% lager ligt dan het gehalte dat in de gangbare praktijk gebruikt

wordt. Een andere opvallende bemerking in dit experiment was dat de dieren die het laagste

eiwitgehalte in het voeder hadden, toch evenveel eiwit per dag opnamen als de groep met een

medium eiwitgehalte. Dit suggereert dat de dieren compenseren voor een beperkt eiwittekort

144

met een grotere voederopname. Dit was opvallend, temeer daar er bij alle

behandelingsgroepen al een grote eetlust werd gezien.

In twee volgende experimenten werden de invloeden van een biologische voeding op

zoötechnische prestaties, karkaskwaliteit en vleeskwaliteit in een gangbare en een biologische

huisvesting bekeken.

In twee stallen, een biologische en een gangbare, werd aan de helft van de dieren een

biologisch en aan de andere helft een gangbaar voeder gegeven. Er werd driefasenvoedering

gebruikt. De voeders werden isocalorisch geformuleerd. In geen van de voeders werden

voederantibiotica gebruikt. Het biologisch voeder werd geproduceerd volgens de wetgeving

op biologische landbouw. De voeders werden isoenergetisch geformuleerd, maar verschilden

wel wat betreft darmverteerbaar-lysinegehalte. Dit was 10% lager in het biologische voeder,

aangezien verondersteld werd dat dit het dichtst aanleunde bij de behoeften in de biologische

stal.

De twee experimenten (experiment 2 en 3) werden jaar op jaar uitgevoerd, telkens in het

voorjaar. In experiment 2 waren alle biggen afkomstig van eenzelfde bedrijf, met dus dezelfde

genetische achtergrond (kruising van een Piétrain beer met een (Belgisch landras x Duroc)

zeug). De dieren die op de proefhoeve in de biostal kwamen waren echter biologisch

opgegroeid (geboren in iglo’s op de weide, gespeend op 7 weken) terwijl de dieren voorzien

voor de gangbare stal op een gangbare manier opgegroeid waren (geboren in de stal, gespeend

op 4 weken). In experiment 3 waren alle biggen afkomstig van de proefhoeve, met dus ook

dezelfde genetische achtergrond (eindkruisingen van Seghers hybrid, nu Rattlerow Seghers),

maar ook dezelfde omstandigheden van geboorte tot spenen. Een week na spenen werd de

groep die voorzien werd voor de biologische stal naar deze huisvesting gebracht, waarbij alle

dieren een biologisch voeder kregen tot de start van de proef (+/- 20 kg).

Het belangrijkste effect dat werd gezien in beide proeven was de grotere voederopname en

snellere groei in de biologische huisvesting. De voederconversie verschilde niet tussen beide

huisvestingstypes. Deze snelle groei leidde in experiment 3 tot vettere karkassen en dus lagere

vleespercentages bij de biologisch gehuisveste dieren. In experiment 2 werd er geen verschil

gemeten wat betreft vleespercentage, wat wil zeggen dat de hogere voederopname gepaard

ging met een evenredige extra mager-vleesaanzet per dag. De maximale eiwitaanzetcapaciteit

was bij de dieren in dit experiment dus nog niet bereikt in de gangbare stal. In het derde

experiment was dit duidelijk wel het geval. De keuze van het ras zal dus ook in biologische

systemen erg belangrijk zijn.

145

De effecten van voeding op groei en voederconversie waren al bij al beperkt. In experiment 2

werd weer duidelijk het effect van dvLYS-gehalte op voederconversie waargenomen, maar dit

werd niet gezien in experiment 3. In de tweede en derde groeifase werden geen verschillen

gevonden wat betreft voederconversie tussen het biologisch voeder en het gangbare voeder.

Vleeskwaliteit was niet consistent beïnvloed door voeding of huisvesting. Waar in het tweede

experiment invloeden konden worden aangetoond van zowel huisvesting als voeding (kleur,

pH, intramusculair vet), werd dit niet herhaald in experiment 3. De belangrijkste bevinding

van de vleeskwaliteitsmetingen is dat in alle proeven deze binnen normale waarden lagen, en

dat daarom in de biologische vleesvarkensteelt vlees kan geproduceerd worden van een

normale kwaliteit.

In experiment 3 werden specifieke antistoffen gemeten tegen een intramusculair ingespoten

lichaamsvreemd antigen (bovien thyroglobuline) als maat voor de specifieke immuunrespons.

Hiervoor werd tweemaal thyroglobuline ingespoten met 3 weken tussentijd en op

verschillende tijdstippen bloed genomen om thyroglobuline specifieke IgG, IgA en IgM te

bepalen. In de bloedstalen werd ook haptoglobine bepaald, een acute-faseproteïne dat wordt

gevormd in de eerste fase van de afweer, bij fysische stress. Bij het slachten werd ook het

lactaatgehalte in het bloed bepaald, als een maat voor fysische stress.

Biologische voeding had geen invloed op deze parameters. In de gangbare stal was er een iets

hogere IgG-respons 3 weken na de eerste injectie. Haptoglobine verschilde enkel tussen de

huisvestingstypes op het moment van slachten. Dit ging gepaard met een hoger lactaatgehalte

in het bloed van de gangbaar gehuisveste dieren. De dieren in de biologische stal leken dus

een verhoogde weerstand te vertonen tegen de fysische stress rond transport en slachten.

In een tweede deel (experiment 4 en 5)werd het gebruik van CCM in een biologische

varkensstal geëvalueerd. Hiervoor werden twee experimenten (experiment CCM1 en CCM2)

uitgevoerd in de biologische stal met 36 dieren (9 hokken van 4 dieren). Bij 3 hokken werd

0%, bij 3 hokken 20% en bij 3 hokken 40% CCM (op verse-stofbasis) ingemengd in het

voeder. Het verschil tussen experiment 4 en 5 is dat in experiment 4 één krachtvoeder werd

gebruikt, dat voldoende eiwit bevatte zodat zelfs bij een krachtvoeder:CCM verhouding van

60:40 de aminozuren niet limiterend zouden zijn. In experiment 5 werden 3 verschillende

voeders geformuleerd, zodanig dat ze met respectievelijk 0, 20 of 40% CCM toegevoegd

telkens dezelfde nutriëntensamenstelling (energie en darmverteerbare essentiële aminozuren)

zouden hebben. Inmenging van CCM tot 40% was mogelijk zonder verlies van productiviteit

of kwaliteit. In de praktijk zal het inmengingpercentage beperkt worden door het lage

eiwitgehalte in de CCM. Door het hogere vochtgehalte in de CCM kan in sommige gevallen

146

de dagelijkse energieopname beperkt worden door het voederen van CCM. Het inmengen

van CCM had een invloed op de immuunrespons: de thyroglobuline-specifieke IgG respons

daalde bij toevoeging van CCM aan het voeder. Hoewel deze daling gecorreleerd was met een

daling van het vitamine A gehalte in het voeder, kon het effect van CCM toevoeging op

immunocompetentie niet toegewezen worden aan één specifieke factor.

De belangrijkste conclusies uit dit werk zijn:

• Biologische varkensteelt is technisch mogelijk zonder een verlies aan kwaliteit.

• Een voeder met een darmverteerbaar-lysinegehalte overeenkomend met het medium

eiwit voeder in het eerste experiment, kan worden gebruikt vanaf 40 kg. Dit komt

overeen met een voeder met 18% ruw eiwit en 0.65% dvLYS (NEv= 9.2 MJ/kg)

tussen 40 and 70kg lichaamsgewicht en 16% ruw eiwit en 0.59% dvLYS (NEv= 9.1

MJ/kg) voor groeiende varkens tussen 70 and 110 kg.

• Dieren in een biologische huisvesting toonden een grote eetlust, die de verwachte

extra energiekost overcompenseerde.

• Biggen in de eerste groeifase (20-40kg) blijken ook in een biologische huisvesting erg

gevoelig aan het darmverteerbaar-lysinegehalte.

• Er konden geen verschillen aangetoond worden tussen biologische en gangbare

voeding wat betreft immuunstatus. Om dit te beïnvloeden zullen specifieke

ingrediënten moeten worden toegevoegd.

• CCM is een praktisch bruikbaar element in biologische varkensvoeding.

147

REFERENCES

AOAC. 1980. Official methods of analysis of the Association of Official Analytical

Chemists, 13th ed. Arlington, VA.

Apple, J. K. and Craig, J. V., 1992. The Influence of Pen Size on Toy Preference of

Growing Pigs. Applied Animal Behaviour Science 35, 149-155.

Arellano, P. E., Pijoan, C., Jacobson, L. D., Algers, B., 1992. Stereotyped Behavior, Social

Interactions and Suckling Pattern of Pigs Housed in Groups Or in Single Crates. Applied

Animal Behaviour Science 35, 157-166.

Arey, D. S., 1993. The effect of bedding on the behavioural and welfare of pigs. Animal

Welfare 2, 235-246.

Arey, D. S. and Edwards, S. A., 1998. Factors influencing aggression between sows after

mixing and the consequences for welfare and production. Livestock Production Science 56,

61-70.

Arthur, R. D., Brumm, M. C., Christenson, R. K., Crenshaw, J. D., Curtis, S. E., Gonyou,

H. C., Hines, R. H., Jesse, G. W., Johnston, L. J., Jones, H. W., Liebbrandt, V. D., Libal, G.

W., Mahan, D. C., Mayrose, V. B., Moser, R. L., Shurson, G. C., Thulin, A. J., Zimmerman,

D. R., Baumgardt, B. R., 1993. Space Requirements of Barrows and Gilts Penned Together

from 54 to 113 Kilograms. Journal of Animal Science 71, 1088-1091.

Asami, D. K., Hong, Y. J., Barrett, D. M., Mitchell, A. E., 2003. Comparison of the total

phenolic and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry, and

corn grown using conventional, organic, and sustainable agricultural practices. Journal of

Agricultural and Food Chemistry 51, 1237-1241.

Barnett, J. L. and Hemsworth, P. H., 1990. The Validity of Physiological and Behavioral

Measures of Animal-Welfare. Applied Animal Behaviour Science 25, 177-187.

Baumann, H. and Gauldie, J., 1994. The Acute-Phase Response. Immunology Today 15,

74-80.

Beattie, V. E., O'Connell, N. E., Moss, B. W., 2000. Influence of environmental

enrichment on the behaviour, performance and meat quality of domestic pigs. Livestock

Production Science 65, 71-79.

Beattie, V. E., Walker, N., Sneddon, I. A., 1995. Effects of environmental enrichment on

behaviour and productivity of growing pigs. Animal Welfare 4, 207-220.

148

Beattie, V. E., Walker, N., Sneddon, I. A., 1996. An investigation of the effect of

environmental enrichment and space allowance on the behaviour and production of growing

pigs. Applied Animal Behaviour Science 48, 151-158.

Beattie, V. E., Weatherup, R. N., Moss, B. W., Walker, N., 1999. The effect of increasing

carcass weight of finishing boars and gilts on joint composition and meat quality. Meat

Science 52, 205-211.

Bikker, P., 2002. Aminozuurvoorziening in vleesvarkensvoeders zonder anti-microbiële

voerbespaarder. Orffa’s varkens Symposium. Breda, 3 oktober 2002.

Blanchard, P. J., Ellis, M., Warkup, C. C., Hardy, B., Chadwick, J. P., Deans, G. A., 1999.

The influence of rate of lean and fat tissue development on pork eating quality. Animal

Science 68, 477-485.

Bolhuis, J. E., Schouten, W. G. P., de Jong, I. C., Schrama, J. W., Cools, A. R., Wiegant,

V. M., 2000. Responses to apomorphine of pigs with different coping characteristics.

Psychopharmacology 152, 24-30.

Bondy, G. S. and Pestka, J. J., 2000. Immunomodulation by fungal toxins. Journal of

Toxicology and Environmental Health-Part B-Critical Reviews 3, 109-143.

Bridi, A., Müller, L., Ribeiro, A. R., 1998. Indoor vs. outdoor-rearing of pigs,

performance, carcass and meat quality. 44th ICOMST. Barcelona, Spain. p. 1056-1057.

Broom, D., 1986. Indicators of poor welfare. British Veterinary Journal 142, 524-526.

Broom, D., 1998. Psychological indicators of stress and welfare. In: A. R. Michell and R.

Ewbank (Eds.) Ethics, Welfare, Law and Market Forces: the Veterinary Interface. pp. 167-

175. U.F.A.W., Wheatampstead, UK.

Broom, D. and Johnson, K. G., 1993. Stress and Animal Welfare. Chapman and Hall,

London,UK.

Cabaret, J., 2003. Animal health problems in organic farming: subjective and objective

assessments and farmers' actions. Livestock Production Science 80, 99-108.

Casteels, M., Vanoeckel, M. J., Boschaerts, L., Spincemaille, G., Boucque, C. V., 1995.

The Relationship Between Carcass, Meat and Eating Quality of 3 Pig Genotypes. Meat

Science 40, 253-269.

Chiba, L. I., Ivey, H. W., Cummins, K. A., Gamble, B. E., 1999. Growth performance and

carcass traits of pigs subjected to marginal dietary restrictions during the grower phase.

Journal of Animal Science 77, 1769-1776.

149

Chiba, L. I., Lewis, A. J., Peo, E. R., 1991. Amino-Acid and Energy Interrelationships in

Pigs Weighing 20 to 50 Kilograms. 1. Rate and Efficiency of Weight-Gain. Journal of Animal

Science 69, 694-707.

Close, W. H. and Poorman, P.K., 1993. Outdoor pigs- their nutrient requirements, appetite

and environmental responses. In: P. C. Garnworthy and D. J. A. Cole (Eds.) Recent Advances

in Animal Nutrition. pp. 175-196. Nottingham University Press, Loughborough, U.K.

Coppieters, W., Van Zeveren, A., Van de Weghe, A., Peelman, L., Boucquet, Y., 1992.

Direct genotyping of stress susceptibility and resistance in pigs by means of a DNA test.

Vlaams Diergeneeskundig Tijdschrift 61, 68-72.

Council of the European Union, 1991. Council Regulation (EEC) No 2092/91 of 24 June

1991 on organic production of agricultural products and indications referring thereto on

agricultural products and foodstuffs. Official Journal L 198 1-15.

Council of the European Union, 1997. Commission Decision of 16 January 1997

authorizing methods for grading pig carcasses in Belgium. Official Journal L 039 17-19.

Council of the European Union, 1999. Council Regulation (EC) No 1804/1999 of 19 July

1999 supplementing Regulation (EEC) No 2092/91 on organic production of agricultural

products and indications referring thereto on agricultural products and foodstuffs to include

livestock production. Official Journal L222 1-27.

CVB, 1998. Table of Feedstuffs. Information about chemical composition, digestibility and

feeding value. Centraal Veevoederbureau, Lelystad, The Netherlands.

Cromwell, G. L., 2001. Antimicrobial and Promicrobial Agents. In: A. J. Lewis and L. L.

Southern (Eds.) Swine Nutrition. pp. 401-426. CRC Press LLC, Boca Raton.

Cunningham-Rundles, S., 2002. Evaluation of the effects of nutrients on immune function.

In: P. C. Calder, C. J. Field, and H. S. Gill (Eds.) Nutrition and immune function. pp. 21-39.

CABI Publishing, Oxon, UK.

Dalgaard, T., Halberg, N., Kristensen, I. S., 1998. Can organic farming help to reduce N-

losses? Experiences from Denmark. Nutrient Cycling in Agroecosystems 52, 277-287.

Day, J. E. L., Kelly, H., Martins, A., Edwards, S. A., 2003. Towards a baseline assessment

of organic pig welfare. Animal Welfare 12, 637-641.

Day, J. E. L., Spoolder, H. A. M., Burfoot, A., Chamberlain, H. L., Edwards, S. A., 2002.

The separate and interactive effects of handling and environmental enrichment on the

behaviour and welfare of growing pigs. Applied Animal Behaviour Science 75, 177-192.

150

de Haer, L. C. M. and Devries, A. G., 1993. Feed-Intake Patterns of and Feed Digestibility

in Growing Pigs Housed Individually Or in Groups. Livestock Production Science 33, 277-

292.

de Jong, I. C., Prelle, I. T., van de Burgwal, J. A., Lambooij, E., Korte, S. M., Blokhuis, H.

J., Koolhaas, J. M., 2000. Effects of environmental enrichment on behavioral responses to

novelty, learning, and memory, and the circadian rhythm in cortisol in growing pigs.

Physiology & Behavior 68, 571-578.

de Jonge, F. H. and Goewie, E. A., 2000. Biologische veehouderij als voorbeeld. In: F. H.

de Jonge and E. A. Goewie (Eds.) In het belang van het dier. Over het welzijn van dieren in

de veehouderij. pp. 90-95. Van Gorcum en Cromp, Assen. Rathenau Instituut, Den Haag.

De Saeger, S., Sibanda, L., Van Peteghem, C., 2003. Analysis of zearalenone and alpha-

zearalenol in animal feed using high-performance liquid chromatography. Analytica Chimica

Acta 487, 137-143.

Eckersall, P. D., 2000. Acute phase proteins as markers of infection and inflammation:

monitoring animal health, animal welfare and food safety. Irish Veterinary Journal 53, 307-

311.

Eckersall, P. D., Saini, P. K., McComb, C., 1996. The acute phase response of acid soluble

glycoprotein, alpha(1)-acid glycoprotein, ceruloplasmin, haptoglobin and C-reactive protein,

in the pig. Veterinary Immunology and Immunopathology 51, 377-385.

Edge, H. L., Bornett, H. L. I., Newton, E., Edwards, S. A., 2004. Alternatives to nose-

ringing in outdoor sows: 2. The provision of edible or inedible overground enrichment.

Animal Welfare 13, 233-237.

Egesel, C. O., Wong, J. C., Lambert, R. J., Rocheford, T. R., 2003. Combining ability of

maize inbreds for carotenoids and tocopherols. Crop Science 43, 818-823.

Ekkel, E. D., Vandoorn, C. E. A., Hessing, M. J. C., Tielen, M. J. M., 1995. The Specific-

Stress-Free Housing System Has Positive Effects on Productivity, Health, and Welfare of

Pigs. Journal of Animal Science 73, 1544-1551.

Ellis, M. and Augspuger, N., 2001. Feed intake in Growing-Finishiung Pigs. In: A. J.

Lewis and L. L. Southern (Eds.) Swine Nutrition. pp. 447-468. CRC Press LLC, Boca raton.

Enfält, A. C., Lundstrom, K., Engstrand, U., 1993a. Early Postmortem pH Decrease in

Porcine M-Longissimus-Dorsi of PSE, Normal and DFD Quality. Meat Science 34, 131-143.

Enfält, A. C., Lundstrom, K., Hansson, I., Karlsson, A., Essengustavsson, B., Hakansson,

J., 1993b. Moderate Indoor Exercise - Effect on Production and Carcass Traits, Muscle

Enzyme-Activities and Meat Quality in Pigs. Animal Production 57, 127-135.

151

Enfält, A. C., Lundstrom, K., Hansson, I., Lundeheim, N., Nystrom, P. E., 1997. Effects of

outdoor rearing and sire breed (Duroc or Yorkshire) on carcass composition and sensory and

technological meat quality. Meat Science 45, 1-15.

Erhard, H. W., Mendl, M., Ashley, D. D., 1997. Individual aggressiveness of pigs can be

measured and used to reduce aggression after mixing. Applied Animal Behaviour Science 54,

137-151.

Essén-Gustavsson, B., Lundstrom, K., Larsson, G., Lindholm, A., Nordin, A. C., Hansson,

I., Thornberg, E., 1988. The effect during growth of moderate exercise on muscle metabolic

characteristics in vivo and relation to meat quality and sensory properties. 34th ICOMST.

Brisbane. p. 27-30.

Fazekas, B., Kis, M., Hajdu, E. T., 1996. Data on the contamination of maize with

fumonisin B-1 and other fusariotoxins in Hungary. Acta Veterinaria Hungarica 44, 25-37.

Ferguson, N. S., Lavers, G., Gous, R. M., 2001. The effect of stocking density on the

responses of growing pigs to dietary lysine. Animal Science 73, 459-469.

Fernandez, X., Monin, G., Talmant, A., Mourot, J., Lebret, B., 1999a. Influence of

intramuscular fat content on the quality of pig meat - 1. Composition of the lipid fraction and

sensory characteristics of m. longissimus lumborum. Meat Science 53, 59-65.

Fernandez, X., Monin, G., Talmant, A., Mourot, J., Lebret, B., 1999b. Influence of

intramuscular fat content on the quality of pig meat - 2. Consumer acceptability of m.

longissimus lumborum. Meat Science 53, 67-72.

Fernandez, X. and Tornberg, E., 1991. A review of the causes of variation in muscle

glycogen content and utimate pH in pigs. Journal of Muscle Foods 2, 209-235.

Fischer, K., Lindner, J. P., 1998. Einzelsaspekte der fütterung nach richtlinien des

ökologischen landbaus im hinblick auf die fleisch- und fettqualität beim schwein. Proceedings

110. VDLUFA-Kongreß. Einfluß von Erzeugung und Verarbeitung auf die Qualität

Landwirtschaftlicher Produkte.Gießen, Germany. VDLUFA-Verlag, 385-388.

Fisher, P., Mellett, F. D., Hoffman, L. C., 2000. Halothane genotype and pork quality. 1.

Carcass and meat quality characteristics of three halothane genotypes. Meat Science 54, 97-

105.

Folch, J., Lees, M., Stanley, S. G. H., 1957. A simple method for the isolation and

purification of total lipids from animal tissues. Journal of biological chemistry 226, 497-509.

Frankenburg, S., Wang, X., Milner, Y., 1998. Vitamin A inhibits cytokines produced by

type 1 lymphocytes in vitro. Cellular Immunology 185, 75-81.

152

Fraser, D., 1984. The role of behaviour in swine production: a review of research. Applied

Animal Ethology 11, 317-339.

Fraser, D., 2003. Assessing animal welfare at the farm and group level: The interplay of

science and values. Animal Welfare 12, 433-443.

Friend, T. H., Knabe, A. D., Tanksley Jr, T. D., 1983. Behavior and performance of pigs

grouped by three different methods at weaning. Journal of Animal Science 57, 1406-1411.

Friesen, K. G., Nelssen, J. L., Goodband, R. D., Tokach, M. D., Unruh, J. A., Kropf, D. H.,

Kerr, B. J., 1994. Influence of Dietary Lysine on Growth and Carcass Composition of High-

Lean-Growth Gilts Fed from 34 to 72 Kilograms. Journal of Animal Science 72, 1761-1770.

Furuya, S., Yamamoto, A., Itoh, M., Aoki, Y., 2001. Use of acid-insoluble ash added with

celite as a marker for determining digestibility in pigs. Japanese Journal of Swine Science 38,

171-176.

Gade, P. B., 2002. Welfare of animal production in intensive and organic systems with

special reference to Danish organic pig production. Meat Science 62, 353-358.

Gandemer, G., Pichou, D., Bougennec, B., Caritez, J. C., Berge, P., Briand, E., Legault, C.,

1990. Influence du système d'élevage et du genotype sur la composition chimique et les

qualités organoleptiques du muscle Longissimus chez le porc. Journées de la recherche

porcine en France 22, 101-110.

Gentry, J. G., McGlone, J. J., Blanton, J. R., Miller, M. F., 2002a. Alternative housing

systems for pigs: Influences on growth, composition, and pork quality. Journal of Animal

Science 80, 1781-1790.

Gentry, J. G., McGlone, J. J., Blanton, J. R., Miller, M. F., 2002b. Impact of spontaneous

exercise on performance, meat quality, and muscle fiber characteristics of growing/finishing

pigs. Journal of Animal Science 80, 2833-2839.

Gentry, J. G., McGlone, J. J., Miller, M. F., Blanton, J. R., Jr., 2004. Environmental effects

on pig performance, meat quality, and muscle characteristics. Journal of Animal Science 82,

209-217.

Geor, R. J., Mccutcheon, L. J., Shen, H., 1999. Muscular and metabolic responses to

moderate-intensity short-term training. Equine Veterinary Journal Suppl 30, 311-317.

Geverink, N. A., de Jong, I. C., Lambooij, E., Blokhuis, H. J., Wiegant, V. M., 1999.

Influence of housing conditions on responses of pigs to preslaughter treatment and

consequences for meat quality. Canadian Journal of Animal Science 79, 285-291.

153

Gomez, R. S., Lewis, A. J., Miller, P. S., Chen, H. Y., 2000. Growth performance and

digestive and metabolic responses of gilts penned individually or in groups of four. Journal of

Animal Science 78, 597-603.

Gomez, R. S., Lewis, A. J., Miller, P. S., Chen, H. Y., Diedrichsen, R. M., 2002. Body

composition and tissue accretion rates of barrows fed corn-soybean meal diets or low-protein,

amino acid-supplemented diets at different feeding levels. Journal of Animal Science 80, 654-

662.

Guy, J. H., Rowlinson, P., Chadwick, J. P., Ellis, A., 2002a. Behaviour of two genotypes of

growing-finishing pig in three different housing systems. Applied Animal Behaviour Science

75, 193-206.

Guy, J. H., Rowlinson, P., Chadwick, J. P., Ellis, M., 2002b. Growth performance and

carcass characteristics of two genotypes of growing-finishing pig in three different housing

systems. Animal Science 74, 493-502.

Guy, J. H., Rowlinson, P., Chadwick, J. R., Ellis, M., 2002c. Health conditions of two

genotypes of growing-finishing pig in three different housing systems: implications for

welfare. Livestock Production Science 75, 233-243.

Haest, J., 1999. Bioproducten naar 5% van de voedingsmarkt in Europa. Studiedag

Biologische Voeding: Quo Vadis? Ingenieurshuis-KVIV, Antwerpen. 23-9-1999.

Hale, O. M., Newton, G. L., Haydon, K. D., 1986. Effect of Diet and Exercise on

Performance, Carcass Traits and Plasma Components of Growing-Finishing Barrows. Journal

of Animal Science 62, 665-671.

Hansson, I., Hamilton, C., Ekman, T., Forslund, K., 2000. Carcass quality in certified

organic production compared with conventional livestock production. Journal of Veterinary

Medicine Series B-Infectious Diseases and Veterinary Public Health 47, 111-120.

Harmon, B. G., Miller, E. R., Hoefer, A., Ullrey, D. E., Luecke, R. W., 1963. Relationship

of specific nutrient deficiencies to antibody production in swine. Journal of Nutrition 79, 263-

268.

Henckel, P., Oksbjerg, N., Erlandsen, E., Barton-Gade, P., Bejerholm, C., 1997. Histo- and

biochemical characteristics of the Longissimus dorsi muscle in pigs and their relationships to

performance and meat quality. Meat Science 47, 311-321.

Hennig, I., 1998. Der aktuelle Fall: Primäre Parakeratose in einem ökologischen

wirtschaftenden Betrieb. Deutsche Tierärztliche Wochenschrift 105, 357.

Henry, Y., 1985. Dietary Factors Involved in Feed-Intake Regulation in Growing-Pigs - A

Review. Livestock Production Science 12, 339-354.

154

Hicks, T. A., McGlone, J. J., Whisnant, C. S., Kattesh, H. G., Norman, R. L., 1998.

Behavioral, endocrine, immune, and performance measures for pigs exposed to acute stress.

Journal of Animal Science 76, 474-483.

Hill, J. D., McGlone, J. J., Fullwood, S. D., Miller, M. F., 1998. Environmental enrichment

influences on pig behavior, performance and meat quality. Applied Animal Behaviour

Science 57, 51-68.

Hodgeson, D. R. and R. Rose. 1994. The athletic horse. W.B. Saunders Company,

Philadephia.

Hodgson, R. R., Davis, G. W., Smith, G. C., Savell, J. W., Cross, H. R., 1991.

Relationships Between Pork Loin Palatability Traits and Physical Characteristics of Cooked

Chops. Journal of Animal Science 69, 4858-4865.

Hoffman, L. C., Styger, E., Muller, M., Brand, T. S., 2003. The growth and carcass and

meat characteristics of pigs raised in a free-range or conventional housing system. South

African Journal of Animal Science 33, 166-175.

Honikel, K. O., 1987. How to measure the water-holding capacity of meat?

Recommendation of standardized methods. In: P. V. Tarrant, G. Eikelenboom, and G. Monin

(Eds.) Evaluation and control of meat quality in pigs. pp. 129-142. Martinus Nijhof,

Dordrecht, The Netherlands.

Hoste, R., Kampshof, J., Bosch, C., de Junker, T., Steverink, M., 2000.

Kostprijsberekening biologische vleesvarkens en biggen. Uitgave: Platform Biologica.

Hughes, D. A., 2002. Antioxidant vitamins and immune function. In: P. C. Calder, C. J.

Field, and H. S. Gill (Eds.) Nutrition and immune function. pp. 171-191. CABI Publishing,

Oxon, UK.

Hyun, Y., Ellis, M., Johnson, R. W., 1998a. Effects of feeder type, space allowance, and

mixing on the growth performance and feed intake pattern of growing pigs. Journal of Animal

Science 76, 2771-2778.

Hyun, Y., Ellis, M., Riskowski, G., Johnson, R. W., 1998b. Growth performance of pigs

subjected to multiple concurrent environmental stressors. Journal of Animal Science 76, 721-

727.

ISO, 1973. Determination of free fat content in meat and meat products.

Johnson, A. K., Morrow-Tesch, J. L., McGlone, J. J., 2001. Behavior and performance of

lactating sows and piglets reared indoors or outdoors. Journal of Animal Science 79, 2571-

2579.

155

Jorgensen, P. F. and Hyldgaard-Jensen, J. F., 1975. The effect of physical training on

skeletal muscle enzyme composition in pigs. Acta Veterinaria Scandinavica 16, 368-378.

Kauffman, R. G., Eikelenboom, G., van der Wal, P. G., Merkus, G., Zaar, M., 1986. The

use of filter paper to estimate drip loss of porcine musculature. Meat Science 18, 191-200.

Kelley, K. W., 1980. Stress and immune function: a bibliographic review. Annales de

recherche veterinaire 11, 445-478.

Kienzle, E., Groose, B. E., Ganter, M., Fuhrmann, H., Stockhofe-zur, W. N., 1993.

Nutrition disorders in fattening pigs in an "organic" facility. Tierarztliche Praxis 21, 521-523.

Kirchmann, H. and Witter, E., 1989. Ammonia Volatilization During Aerobic and

Anaerobic Manure Decomposition. Plant and Soil 115, 35-41.

Klasing, K. C., 1998. Nutritional modulation of resistance to infectious diseases. Poultry

Science 77, 1119-1125.

Klont, R. E., Hulsegge, B., Hoving-Bolink, A. H., Gerritzen, M. A., Kurt, E., Winkelman-

Goedhart, H. A., de Jong, I. C., Kranen, R. W., 2001. Relationships between behavioral and

meat quality characteristics of pigs raised under barren and enriched housing conditions.

Journal of Animal Science 79, 2835-2843.

Kracht, W., Matzke, W., Leonhardt, C., 1984. Ergebnisse zum Futterwert von Maiskorn-

Spindel-Gemisch und Hinweise zum einsatz in der Schweinemast. Tierzucht 38, 422-426.

Kritas, S. K. and Morrison, R. B., 2004. An observational study on tail biting in

commercial grower-finisher barns. Journal of Swine Health and Production 12, 17-22.

Lambooij, E., Hulsegge, B., Klont, R. E., Winkelman-Goedhart, H. A., Reimert, H. G. M.,

Kranen, R. W., 2004. Effects of housing conditions of slaughter pigs on some post mortem

muscle metabolites and pork quality characteristics. Meat Science 66, 855-862.

Lebret, B., Massabie, P., Granier, R., Juin, H., Mourot, J., Chevillon, P., 2002. Influence of

outdoor rearing and indoor temperature on growth performance, carcass, adipose tissue and

muscle traits in pigs, and on the technological and eating quality of dry-cured hams. Meat

Science 62, 447-455.

Lefaucheur, L., 2004. Myofiber typing and pig meat production. Slovenian Veterinary

Research 38, 5-33.

Lewis, P. K., Rakes, L. Y., Brown, C. J., Noland, P. R., 1989. Effect of Exercise and Pre-

Slaughter Stress on Pork Muscle Characteristics. Meat Science 26, 121-129.

Lindahl, G., Lundstrom, K., Tornberg, E., 2001. Contribution of pigment content,

myoglobin forms and internal reflectance to the colour of pork loin and ham from pure breed

pigs. Meat Science 59, 141-151.

156

Lindermayer, H. and Propstmeier, G., 1994. Leistungsforderer über die gesamte Mastduer?

Kraftfutter 12, 479-481.

Llames, C. R. and Fontaine, J., 1994. Determination of amino acids in feeds: collaborative

study. Journal AOAC International 77, 1362-1402.

Lovatto, P. A. and Sauvant, D., 2002. Méta-analyse et modelisation de l'ingestion

volontaire chez le porc. Journées de la Recherche Porcine 34, 129-134.

Marlin, D. and Nankervis, K. 2002. Equine exercise physiology. Blackwell Science Ltd..

Mcphee, C. P., Williams, K. C., Daniels, L. J., 1991. The Effect of Selection for Rapid

Lean Growth on the Dietary Lysine and Energy-Requirements of Pigs Fed to Scale. Livestock

Production Science 27, 185-198.

Meuwissen, M., van der Lans, I. A., 2004. Trade-offs between consumer concerns: an

application for pork production. 84th EAAE seminar, Food Safety in a Dynamic World, Zeist,

The Netherlands, 8-11 February 2004.

Ministrial Decree of August 7th, 1997 [Ministerieel besluit van 7 augustus 1997 tot

vaststelling van aanvullende voorwaarden tot erkenning van organismen belast met de

controle op de biologische productiemethode en aanduidingen dienaangaande op

landbouwproducten en levensmiddelen]. Belgisch Staatsblad van 29 augustus 1997, 22106-

22107.

Ministrial Decree of October 30th, 1998 [Ministerieel besluit van 30 oktober 1998 tot

vaststelling van de voorschriften betreffende de biologische productie in de dierlijke sector].

Belgisch Staatsblad van 1 december 1998, 38294-38299.

Ministrial Decree of August, 19th, 2000 [Ministerieel besluit van 19 augustus 2000 tot

wijziging van het ministerieel besluit van 30 oktober 1998 tot vaststelling van de

voorschriften betreffende de biologische productie in de dierlijke sector]. Belgisch Staatsblad

van 22 september 2000, 32113-32121

Moberg, G. P. 2000. Biological response to stress: implications for animal welfare. In: G.

P. Moberg and J. A. Mench (Eds.) The biology of Animal Stress: basic principles and

implications for animal welfare. pp. 1-21. CAB International, Oxon, UK.

Moberg, G. P. and J. A. Mench. 2000. The biology of Animal Stress: basic principles and

implications for animal welfare. CAB International, Oxon, UK.

Morgan, C. A., Deans, L. A., Lawrence, A. B., Nielsen, B. L., 1998. The effects of straw

bedding on the feeding and social behaviour of growing pigs fed by means of single-space

feeders. Applied Animal Behaviour Science 58, 23-33.

157

Mouttotou, N., Hatchell, F. M., Green, L. E., 1999. Foot lesions in finishing pigs and their

associations with the type of floor. Veterinary Record 144, 629-632.

Muirhead, M. R. and J. L. Alexander. 1997. Managing pig health and the treatment of

disease. 5M enterprises Ltd., Sheffield, UK.

Nakai, H., Saito, F., Ikeda, T., Ando, S., Komatsu, A., 1975. Standard models of pork

colour. Bulletin of National Institute of Animal Industry 29, 69-74.

Nansen, P. and Roepstorff, A., 1999. Parasitic helminths of the pig: factors influencing

transmission and infection levels. International Journal for Parasitology 29, 877-891.

National Research Council, 1998. Nutrient requirements of swine, 10th ed.. National

Academy Press, Washington, DC, USA.

Ngapo, T. M., Dransfield, E., Martin, J.-F., Magnusson, M., Bredahl, L., Nute, G. R.,

2004a. Consumer perceptions: pork and pig production. Insights from France, England,

Sweden and Denmark. Meat Science 66, 125-134.

Ngapo, T. M., Martin, J. F., Dransfield, E., 2004b. Consumer choices of pork chops:

results from three panels in France. Food Quality and Preference 15, 349-359.

Noblet, J., Ledividich, J., Bikawa, T., 1985. Interaction Between Energy-Level in the Diet

and Environmental-Temperature on the Utilization of Energy in Growing-Pigs. Journal of

Animal Science 61, 452-459.

NRC, 1998. See National Research Council, 1998.

O'Connell, N. E. and Beattie, V. E., 1999. Influence of environmental enrichment on

aggressive behaviour and dominance relationships in growing pigs. Animal Welfare 8, 269-

279.

Ödberg, F. O., 1978. Abnormal behaviours: (stereotypies). Proceedings of the 1st World

Congress on Ethology Applied to Zootechnics, 475-480. Madrid, Industrias Graficas España.

(Editorial Garsi) .

Olsson, V., Andersson, K., Hansson, I., Lundstrom, K., 2003. Differences in meat quality

between organically and conventionally produced pigs. Meat Science 64, 287-297.

Ooghe, W., 1983. On the influence of hydrogen peroxide on the amino acid composition

of food proteins. Proceedings of Euro Food Chem II, Rome, Italy, 315-321.

Oswald, I. P. and Comera, C., 1998. Immunotoxicity of mycotoxins. Revue de Medecine

Veterinaire 149, 585-590.

Oude Groeniger, C. and Groenestein, C., 2000. Biologische varkensstallen en

ammoniakemissie. Biologische varkenshouderij 14-17.

158

Oude Ophuis, P.A.M., 1994. Sensory evaluation of “free range” and regular pork meat

under different conditions of experience and awareness. Food Quality and Preference 5, 173-

178.

Pearce, G. P., Paterson, A. M., Pearce, A. N., 1989. The Influence of Pleasant and

Unpleasant Handling and the Provision of Toys on the Growth and Behavior of Male Pigs.

Applied Animal Behaviour Science 23, 27-37.

Pekas, J. C., Yen, J. T., Pond, W. G., 1983. Gastrointestinal, Carcass and Performance

Traits of Obese Versus Lean Genotype Swine - Effect of Dietary Fiber. Nutrition Reports

International 27, 259-270.

Petersen, H. H., Dideriksen, D., Christiansen, B. M., Nielsen, J. P., 2002a. Serum

haptoglobin concentration as a marker of clinical signs in finishing pigs. Veterinary Record

151, 85-89.

Petersen, H. H., Ersboll, A. K., Jensen, C. S., Nielsen, J. P., 2002b. Serum-haptoglobin

concentration in Danish slaughter pigs of different health status. Preventive Veterinary

Medicine 54, 325-335.

Petersen, J. S., Henckel, P., Maribo, H., Oksbjerg, N., Sorensen, M. T., 1997. Muscle

metabolic traits, post mortem pH-decline and meat quality in pigs subjected to regular

physical training and spontaneous activity. Meat Science 46, 259-275.

Petersen, J. S., Henckel, P., Oksbjerg, N., Sorensen, M. T., 1998a. Adaptations in muscle

fibre characteristics induced by physical activity in pigs. Animal Science 66, 733-740.

Petersen, J. S., Oksbjerg, N., Jorgensen, B., Sorensen, M. T., 1998b. Growth performance,

carcass composition and leg weakness in pigs exposed to different levels of physical activity.

Animal Science 66, 725-732.

Petersen, V., Simonsen, H. B., Lawson, L. G., 1995. The Effect of Environmental

Stimulation on the Development of Behavior in Pigs. Applied Animal Behaviour Science 45,

215-224.

Petrie, A. and Watson P., 1999. Statistics for Veterinary and Animal Science. Blackwell

Science Ltd, Oxford.

Pinton, P., Royer, E., Accens, F., Marin, D., Guelfi, J.-F., Bourgès-Abella, N., Granier, R.,

Grosjean, F., Oswald, I. P., 2004. Effects of feeding growing or finishing pigs with

deoxynivalenol (DON) naturally contaminated feed on growth performance and

immunological status. Journées de la Recherche Porcine 36, 301-308.

159

Raes, K., De Smet, S., Demeyer, D., 2001. Effect of double-muscling in Belgian Blue

young bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic

acid and polyunsaturated fatty acids. Animal Science 73, 253-260.

Randolph, J. H., Cromwell, G. L., Stahly, T. S., Kratzer, D. D., 1981. Effects of Group-

Size and Space Allowance on Performance and Behavior of Swine. Journal of Animal

Science 53, 922-927.

Renand, G., Larzul, C., Bihan-Duval, E., Le Roy, P., 2003. Genetic improvement of meat

quality in the different livestock species: present situation and prospects. Productions

Animales 16, 159-173.

Rosenvold, K., Petersen, J. S., Laerke, H. N., Jensen, S. K., Therkildsen, M., Karlsson, A.

H., Moller, H. S., Andersen, H. J., 2001. Muscle glycogen stores and meat quality as affected

by strategic finishing feeding of slaughter pigs. Journal of Animal Science 79, 382-391.

Royal Decree of April 17th, 1992 [Koninklijk besluit van 17 april 1992 inzake de

biologische productiemethoden en aanduidingen dienaangaande op landbouwproducten en

levensmiddelen]. Belgisch Staatsblad van 20 mei 1992, 11695-11697.

Royal Decree of July 10th, 1998 [Koninklijk besluit van 10 juli 1998 tot wijziging van het

koninklijk besluit van 17 april 1992 inzake de biologische productiemethoden en

aanduidingen dienaangaande op landbouwproducten en levensmiddelen]. Belgisch Staatsblad

van 1 december 1998, 38291-38292.

Rushen, J., 2003. Changing concepts of farm animal welfare: bridging the gap between

applied and basic research. Applied Animal Behaviour Science 81, 199-214.

Rushen, J., 2004. Stereotypies, agression and the feeding schedules of tethered sows.

Applied Animal Behaviour Science 14, 137-147.

Sellier, P., Houix, Y., Desmouli, B., Henry, Y., 1974. Preliminary Observations on

Relationship Between Nutrition Status and Genotype in Gilts. Annales de Zootechnie 23, 405-

406.

Stark, K. D. C., 2000. Epidemiological investigation of the influence of environmental risk

factors on respiratory diseases in swine - A literature review. Veterinary Journal 159, 37-56.

SPSS. Release 11.0.1 and 12.0. SPSS Inc., 444N. Michigan Avenue, Chicago, IL, 60611.

Sundrum, A., Butfering, L., Henning, M., Hoppenbrock, K. H., 2000a. Effects of on-farm

diets for organic pig production on performance and carcass quality. Journal of Animal

Science 78, 1199-1205.

160

Sundrum, A., Kulig, B., Biederman, G., 2000b. Feeding strategy in organic farming to

improve the quality of pork. IFOAM 2000-The world grows organic. Proceedings 13th

International IFOAM Scienctific Conference, 370..

Susenbeth, A. and Keitel, K., 1988. Partition of whole body protein in different body

fractions and some constants in body composition in pigs. Livestock Production Science 20,

37-52.

Swamy, H. V. L. N., Smith, T. K., MacDonald, E. J., Boermans, H. J., Squires, E. J., 2002.

Effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on

swine performance, brain regional neurochemistry, and serum chemistry and the efficacy of a

polymeric glucomannan mycotoxin adsorbent. Journal of Animal Science 80, 3257-3267.

Tarladgis, B. G., Watts, B. M., Younathan, M. T., Dugan, L. R., 1960. A distillation

method for the quantitative determination of malonaldehyde in foods. Journal of the American

Oil Chemist's Society 37, 44-48.

Thamsborg, S. M., Roepstorff, A., Larsen, M., 1999. Integrated and biological control of

parasites in organic and conventional production systems. Veterinary Parasitology 84, 169-

186.

Thielen, C. and Kienzle, E., 1994. The feeding of "organic swine"--a field study.

Tierarztliche Praxis 22, 450-459.

Thomke, S., Madsen, A., Mortensen, H. P., Sundstol, F., Vangen, O., Alaviuhkola, T.,

Andersson, K., 1995. Dietary Energy and Protein for Growing Pigs .1. Performance and

Carcass Composition. Acta Agriculturae Scandinavica Section A-Animal Science 45, 45-53.

Vaarst, M., Roepstorff, A., Feenstra, A., Hogedal, P., Larsen, V. A., Lauritsen, H. B.,

Hermansen, J. E., 1999. Animal health and welfare aspects of organic pig production.

Horsens, Denmark. Proceedings from NJF-seminar No. 303. 16-9-1999.

van der Wal, P. G., Mateman, G., Devries, A. W., Vonder, G. M. A., Smulders, F. J. M.,

Geesink, G. H., Engel, B., 1993. Scharrel (Free Range) Pigs - Carcass Composition, Meat

Quality and Taste-Panel Studies. Meat Science 34, 27-37.

Van Oeckel, M. J., Warnants, N., Boucque, C. V., 1999. Measurement and prediction of

pork colour. Meat Science 52, 347-354.

Van Oeckel, M.J., 1999. The quality of pork. Thesis submitted in fulfilment of the

requirements for the degree of doctor (PhD) in Applied biological Sciences: Agricultural

Sciences. Ghent University.

161

van Vliet, C., Goewie, E. A., 1999. Is biologische voeding gezonder dan gangbare?

Samenvatting van een literatuurstudie. Studiedag Biologische Voeding: Quo Vadis?

Ingenieurshuis-KVIV, Antwerpen. 23-9-1999.

Van Zaane, D. and Hulst, M. M., 1987. Monoclonal antibodies against porcine

imunoglobulin isotypes. Veterinary Immunology and Immunopathology 16, 23-36.

Verbeke, W., De Smet, S., Vackier, I., Van Oeckel, M. J., Warnants, N., Van Kenhove, P.,

200. Role of intrinsic search cues in the formation of consumer preferences and choice for

pork chops. Meat Science 69, 343-354.

Wang, Y. W., Cherian, G., Sunwoo, H. H., Sim, J. S., 2000. Dietary polyunsaturated fatty

acids significantly affect laying hen lymphocyte proliferation and immunoglobulin G

concentration in serum and egg yolk. Canadian Journal of Animal Science 80, 597-604.

Warnants, N., Van Oeckel, M. J., De Paepe, M., 2000. Bietenpulp in vleesvarkensvoeders.

Landbouw & Techniek 5, 36-37.

Warriss, P. D., Bevis, E. A., Ekins, P. J., 1989. The relationship between glycogen stores

and muscle ultimate pH in commercially slaughtered pigs. British Veterinary Journal 145,

378-383

Warriss, P. D., Brown, S. N., Adams, S. J. M., Corlett, I. K., 1994. Relationships between

subjective and objective assessments of stress at slaughter and meat quality in pigs. Meat

Science 38, 329-340.

Warriss, P. D., Kestin, S. C., Robinson, J. M., 1983. A note on the influence of rearing

environment on meat quality in pigs. Meat Science 9, 271-279.

Weber, R., Zárate, A. V., 2000. Welfare of fattening pigs in different husbandry systems.

Blokhuis, H. J., Ekkel, E. D., and Wecksler, B. 117-125Wageningen, the Netherlands,

Wageningen Pers. 21-8-2000.

Wechsler, B., 1995. Coping and Coping Strategies - A Behavioral View. Applied Animal

Behaviour Science 43, 123-134.

Wecke, C., Lehman, H., Pöhland, U., Jeroch, H., Gebhardt, G., Zimmerman, J., 1990.

Prüfung des Futterwertes von CCM-Silagen in Abhängigkeit vond spindelanteil und

Zerkleinerungsgrad in Untersuchungen an Schweinen. Tierzucht 44, 226-229.

Wemelsfelder, F., Haskell, M., Mendl, M. T., Calvert, S., Lawrence, A. B., 2000. Diversity

of behaviour during novel object tests is reduced in pigs housed in substrate-impoverished

conditions. Animal Behaviour 60, 385-394.

162

Whittemore, E. C., Kyriazakis, I., Emmans, G. C., Tolkamp, B. T., 2001. Tests of two

theories of food intake using growing pigs - 1. The effect of ambient temperature on the

intake of foods of differing bulk content. Animal Science 72, 351-360.

Willer, H. and Richter, T. 2004. 7.4 Europe. In: H. Willer and M. Yussefi (Eds.) The

World of Organic Agriculture 2004. Statistics and Emerging Trends. pp. 93-117. IFOAM,

Bonn, Germany.

Willer, H. and Yussefi, M.. 2000. 6.3 Europe. In: H. Willer and M. Yussefi (Eds.) Organic

Agriculture worldwide. Statistics and Future Prospects. pp. 51-65. Stiftung Ökologie &

Landbau, Bad Dürkheim.

Windhorst, H. W., 2001. Global patterns of pork production and pork trade. Second

virtual conference on Pork Quality. http://www.conferencia.uncnet.br/pork/pork.en.html

Wlcek, S. and Zollitsch, W., 2000. Food-pocessing by-products in swine nutrition-

bakery by-products as a model. 374IFOAM 2000-The world grows organic. Proceedings

13th International IFOAM Scienctific Conference. 2000.

Wolter, B. F., Ellis, M., Curtis, S. E., Augspurger, N. R., Hamilton, D. N., Parr, E. N.,

Webel, D. M., 2001. Effect of group size on pig performance in a wean-to-finish production

system. Journal of Animal Science 79, 1067-1073.

Yen, H. T., Cole, D. J. A., Lewis, D., 1986. Amino-Acid-Requirements of Growing-Pigs.

8. the Response of Pigs from 50-Kg to 90-Kg Live Weight to Dietary Ideal Protein. Animal

Production 43, 155-165.

Youssao, I. A. K., Verleyen, V., Michaux, C., Leroy, P. L., 2002. A comparison of the Fat

Lean Meter (CGM), the ultrasonic device Pie Medical 200 and the Piglog 105 for estimation

of the lean meat proportion in Piétrain carcasses. Livestock Production Science 78, 107-114.

163

DANKWOORD

2000. Na 5 jaar intens studiewerk heb je tijdens je laatste jaar wat tijd om na te

denken. Je kijkt wat rond en hoort dat ergens op een vergeten departement bij een wijze grijze man een project rond biologische varkens zou starten. En hoewel de cursus Dierenvoeding al lang ligt te vergelen tussen de massa’s leerkost op een stoffige zolder besluit je eens te gaan luisteren… De grijze man lijkt al iets meer grootvader-achtig dan in je studentenherinneringen en hij stelt je voor aan z’n rustige goedlachse collega, die voorbestemd lijkt om z’n opvolger te worden. Als je in je onwetendheid vraagt of zo’n project ook naar een doctoraat zou kunnen leiden krijg je een blik van goedkeuring…

2004. Na 4 jaar onderzoek is het project met de ronkende titel “voedingsbehoeften en

productkwaliteit in de biologische vleesvarkenteelt” uitgemond in een doctoraat. Dit was mogelijk door de financiering door het ministerie van Middenstand en Landbouw gedurende de eerste 2 jaar en het IWT (contractueel landbouwkundig onderzoek) tijdens de volgende 2 jaar. Waarvoor dank.

Omdat dit doctoraat zonder hen nooit was geworden wat het is, dank ik: Prof. dr. ir. Geert Janssens. Voor de aanzet en de ontwikkeling van de

projectaanvraag, het ontiegelijke verbeterwerk, de massa’s discussies, maar zeker ook voor zijn voortdurende optimisme en vertrouwen gevende houding. Je hebt gelijk gehad: mijn doctoraat is een feit. Steven Galle. Voor het nuchter verstand en voor je jaren ervaring. Voor de hulp bij het eten afwegen, het in orde houden van de stal, het wegen en bloed nemen bij de biggen… Het is geruststellend te weten dat het verloop van de proeven onder controle is! Julie Raes en Herman de Rycke. Bedankt Julie, voor de samenwerking; onder de deskundige leiding van Herman waren de analyses in orde… En als je iemand zoekt die het belang van juiste staalnames kan inschatten of de relevantie van een variantie kan inschatten: bij Herman ben je aan het juiste adres! Professor De Smet, Katleen Raes, Marc Seynaeve en Daisy Baeyens van de vakgroep dierlijke productie in Melle. Voor de goede samenwerking en de massa’s metingen en analyses, die niet altijd op de meest gunstige tijdstippen verliepen. Professor Cox, Professor Goddeeris en hun medewerkers. Voor de verrijkende discussie over boeiende materie en voor de analyse van de berg plasmastalen. De overige leden van mijn doctoraatsbegeledingscommisie en examencommissie, in het bijzonder Monique Van Oeckel. Voor de constructieve opmerkingen in de loop van het project en bij het afronden van mijn doctoraat.

164

De specialisten uit de biologische sector, Wim Govaerts van BLIVO en Johan Meeus van Molens Dedobbeleer. Dankzij jullie kreeg ik info over de biologische productie, en had ik steeds het nodige proefvoeder. Biocentrum-Agrivet. Hier konden al mjn proeven doorgaan. Een woord van dank voor professor Christiaens en Gerard Eeckhaut die steeds bereid waren oplossingen te zoeken zodat mijn proeven volgens schema konden plaatsvinden. En omdat een doctoraat meer is dan metingen, analyses en interpretaties alleen, een welgemeend woordje van dank voor:

Het labo. Wat doe je als je beu gekeken bent op je pc, of als je de belevenissen van het weekend nog moet vertellen voor je echt in gang kan schieten? Ik ging langs bij Jenny, de SAP specialiste van de dienst (sec) die steeds begaan was met de sfeer op de dienst. Ook de andere collega’s: Myriam, Stephanie en Ans wil ik bedanken, voor de goede werksfeer, maar ook voor de soms zware discussies tijdens de koffiepauze. Natuurlijk mag ik Joany niet vergeten. Je verblijf aan het labo was te kort, maar ik ben blij dat je er enkele maanden rondgelopen hebt. Bart Van den Abeele wil ik danken voor de weekends dat hij de verzorging van de dieren voor zijn rekening nam en voor de hulp bij het nemen van de foto’s. En wat doe je als je pc crasht, een computervirus hardnekkig volhoudt of je je varkens gewoon eens op digitale film wilt vereeuwigen? Ik ging dan langs bij Filip Clompen. Filip, bedankt voor alle hulp bij grote of kleine computerproblemen. Katrien, Jo en Helene. Wat doe je als je de muren oploopt omdat dat ene artikel maar blijft bij een editor liggen, als je even wilt ontspannen na een al dan niet drukke werkdag of als je gewoon eens je petekind wil zien? Ik ben blij dat ik dan in Ledeberg terecht kon. Mede s(up)porters. Wat doe je om de mentale inspanningen weg te spoelen? Ik ging sporten. Bedankt aan alle medeatleten en vrienden, op de piste, in het aquajogbad of op de après-cross. Speciaal dankwoordje voor Dirk, het is niet altijd makkelijk om “nen universitair” te trainen.. De eindredactie. Wat doe je als je een dankwoord wil schrijven, de bladzijden die het meest gelezen worden? Merci Wouter, Davy en Christel voor de hulp bij en het nalezen. M’n ouders, broers en zussen. Zij werden wat in het ongewisse gelaten over de vorderingen van dit proefschrift. Ik hoop dat ze tevreden zijn over dit werk, maar ben er vrij gerust in. Bedankt! Marleen en Christophe. Een dankwoord sluit je af in schoonheid... ‘k ben je niet vergeten Marleen. Een goed jaar na mij arriveerde je op het labo, en gaf mee kleur aan m’n doctoraatsjaren. En ook buiten het werk is het altijd tof bij jou en Christophe te passeren.

165

CURRICULUM VITAE

Sam Millet werd geboren op 5 januari 1976 te Brugge. Na het behalen van het diploma hoger

secundair onderwijs aan het Don Boscocollege in Zwijnaarde (Latijn-Wiskunde), begon hij in

1994 met de studie Diergeneeskunde aan de Universiteit Gent. In 2000 behaalde hij het

diploma van Dierenarts met onderscheiding.

Enkele maanden later trad hij in dienst als wetenschappelijk medewerker bij de vakgroep

Dierenvoeding, Dierlijke genetica, Vee-uitbating en Ethologie. Hier werkte hij gedurende 4

jaar aan het project “Voedingsbehoeften en productkwaliteit in de biologische

vleesvarkensteelt” dat tijdens de eerste 2 jaar werd gefinancierd door het ministerie van

Middenstand en Landbouw en de volgende 2 jaar door het IWT (contractueel

landbouwkundig onderzoek).

Hij behaalde het getuigschrift van de doctoraatsopleiding in 2004.

Sam Millet is auteur of medeauteur van 10 publicaties in internationale tijdschriften. Hij nam

actief deel aan verschillende internationale congressen.