Animal Genetics

ANIMAL GENETICS Differences in animals are brought about by 2 groups of factors: genetic and environmental factors. One set of differences is said to be the animal’s phenotype.

Phenotypes are the physical appearance of the animal. –Color –Size –Shape They can be caused by the environment.

The other reason for the animal’s phenotype is the genotype or the actual genetic makeup of the animal. The only way to control genotype is to control the type of animals used for breeding.

An animal’s characteristics are passed on by its parents. It gets half of its genetic makeup from each parent. 50% from mother 50% from father

Every gene from the male is paired with the same type of gene from the female. –Example: The gene that controls the color of the animal’s coat is made up of a pair of “coat color” genes-1 from father and 1 from mother.

If both genes are the same,that is they both call for a black coat or both call for a white coat, then the genes are said to be homozygous. The animal will be that color. Example: BB is homozygous black

What happens if the father’s gene calls for a black coat and the mother’s gene calls for a white coat?

In this case the genes of the offspring are said to be heterozygous. The color will then be determined by the dominant gene. Example: Bw is heterozygous Black

The determination of the animal ’ s sex Each body cell contains one pair of chromosomes called the sex chromosomes. The female chromosome is referred to as XX. The male chromosome is XY. When the male is divided into sperm it contains either X or Y to meet the female’s X. Therefore, male chromosomes decide the sex of animals.

If a white sow is mated to a black boar what would the offspring look like?

“B” represents the dominant black color gene. The “w” represents the recessive white color gene.

BB x ww

The pigs will be black, but will possess genes for both black and white color.

Bw x ww

Bw x Bw

Bw x BB

Performance Data An animals performance and analysis of ancestry and progeny are valuable tools in determining the animals use for breeding. This information is obtained through the use of data collection and computer analysis.

EPD (Expected Progeny Difference) This is an estimate of the expected performance of an animal’s offspring. Producers look at EPD’s to decide which bull to artificially inseminate their cows to.

Explanation of Performance Records BW(Birth Weight)-birth weight expected WWT(Weaning Weight)-weaning weight at 205 days of age YWT(Yearling Weight)-yearling weight at 365 days of age

EPD ’ s All the EPD’s are compared to the average for that breed. Example- –If the average BW for an Angus bull is 3 and your bull’s BW is 6 then it is expected that calves by your bull will be 3 lbs heavier than average.