OUTBREEDING

By:Arjane Mae Maestrado, Ph.D.

Junemae Libuangan. RA

CONTENTSA. WHAT IS OUTBREEDING

◦PURPOSE◦ADVANTAGES◦DISADVANTAGES◦FACTORS TO CONSIDER◦DIFFERENCE BET INBREEDING AND

OUTBREEDING◦FORMS AND EXAMPLES

OUTBREEDING Breeding of animals of same breed but not

related through blood Between unrelated or distantly related

individuals of a species.

PURPOSE Exploit the genetic phenomenon of

HETEROSIS and COMPLIMENTARITY

Heterosis- where performance of the offsprings are better or worse than the mean of the two parents.

PURPOSE Complimentarity- the phenomenon under which the

progeny inherits advantageous traits from the both parents

SIRI COW (the pest resistant, highly adapted

to the terrain)

JERSEY BULL (known for milk production

better than Siri and high fat content)

JERSEY-SIRI XBRED (milk yield better than Siri, resistance and adaptability

better than pure jersey)

X

ADVANTAGE/S Populations usually show more variation

than inbreeding ones and have a greater potential for adapting to environmental changes.

Increases the number of heterozygous individuals, so disadvantageous recessive characteristics tend to be masked by dominant alleles.

New and high yielding genes can be introduced into the population through out breeding.

They produce some valuable traits

DISADVANTAGE/S Introduction of new genes into population

Animal Discomfort accidentally reproduce traits that are damaging to

the health of the animal Ex. Cows can only produce large amount of milk if

they have large udders. Usually, a product of selective breeding may find it heavy because they have large udders. (Occupytheory.org)

FACTORS TO CONSIDER Breeding objective What and who do we measure Number and which animals to select as

parents Mating

DIFFERENCE BET INBREEDING AND OUTBREEDING

FORMS OF OUTBREEDING Outcrossing- the mating of an individual to

another in the same breed that is not related to it; produces a higher level of heterozygosity

Grading up- the mating of purebred sires to nondescript or grade females and their female offspring generation after generation

Linecrossing- the crossing of rather distinct lines (that may or may not be inbred) of the same breed

FORMS OF OUTBREEDING Crossbreeding─ the mating of animals of different established

breeds─ utilizes these breed differences in a strategic

manner to improve the efficiency of meat, wool, and milk production over pure breeding

─ produce a uniform product

Two Breed Cross Rotational Cross Terminal Cross

Species cross- the crossing of animals of different species