Question

A horse breeder is interested in making genetic progress for racing the mile. She is evaluating three potential selection schemes. Data available for comparing each scheme includes a heritability of 0.35, a repeatability of 0.57, a phenotypic standard deviation of 2.3 seconds, and a phenotypic mean of 130 seconds. Females are selected in the top 80% of the population with an accuracy based on the average of 3 race records, and the generation interval for females is 5 years. The breeder is considering three alternative schemes for selecting males, and each of these schemes will include selecting males in the top 5% of the population. Compare each of these schemes and indicate which approach is the most optimal for maximizing genetic progress.

1. a) Selection based on a single race record of the individual sire with an estimated generation interval of 6 years.

2. b) Selection based on the average of three races of the individual with a generation interval of 6 years.

3. c) Selection based on records of 5 progeny with 3 races each, and a generation interval of 10 years.

Answer 1