Animal Selection

Question 1

expected progeny difference (EPD)

Answer 1

-expected difference between average performance of individuals progeny and average performance of all progeny
-half of the parents breeding value because only half the parents genes will be passed on

Question 2

Accuracy of EPD

Answer 2

-accuracy is only as good as the people measuring the traits
-accuracy increases with larger pool
-0.1-0.99 scale

Question 3

predicted transmitting ability (PTA)

Answer 3

-analogous to EPD but for dairy
-notation may be different
-reliability is expressed as a percent
-breed specific

Question 4

expected breeding value (EBV)

Answer 4

-looks at the individual to assess their genetic merit as a parent
-summation of individual, independent alleles that are transmittable
-EBV=EPD x2

Question 5

Genetic Markers

Answer 5

marker assisted selection
-usually we make decisions based on phenotype or another tool
-we can now test for certain genetic markers of merit
-SNP- single nucleotide polymorphism
- a marker for a deriserable trait
-beef- disease resistance, embryo mortality, ADG
-swine- carcass composition
-allows selection of animals before maturity
-these tools are a great way to compare animals potential without confounding effects

Question 6

Making genetic change- selection

Answer 6

-select animals that meet a pre-determined threshold
-herds and flocks must have variation in order for selection to be effective

Question 7

Making genetic change- mating

Answer 7

-make breeding decisions based on animals
-ex.
-use a sire with high EBV for calving ease on heifers
-use a sire with a high EPD for carcass weight on light-musculed cows