Wagga breeder uses natural mating in a closed stud consisting of 500 breeding co
ID: 142854 • Letter: W
Question
Wagga breeder uses natural mating in a closed stud consisting of 500 breeding cows (age structure is given below).
He is interested in improving milk yield via direct selection for the trait. The heritability (h2) and standard deviation (p) of milk yield is 0.6 and 500 Kg respectively. Assuming a weaning rate of 0.8 and no mortality, calculate:
What are the selected proportions of males and females? (1 mark)
What is the overall generation interval? (1 mark)
What is the expected response to selection per generation? (1 mark)
What is the expected response per year? (1 mark)
What is the effective population size? (1 mark)
What is the rate of inbreeding after 20 years? (1 mark)
If the weaning rate increased to 0.9, would the expected response increase or decrease and why? (1 mark)
Age when progeny are dropped: 2 3 4 5 6 Number of bulls: 2 2 Number of cows: 100 100 100 100 100Explanation / Answer
* Selected proportion of male and female is 1:50
*Overall generation interval is 4 year.
*expected response to selection per generation is 20%
*expected response per year is 50%
*effective population size is 200 breeds
*rate of breeding after 20 year is 400 breeds
*If the weaning rate is increase 0.9,would the expected response will be decreases
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