(Must show working-out) A Wagga breeder uses natural mating in a flock of sheep
ID: 143325 • Letter: #
Question
(Must show working-out)
A Wagga breeder uses natural mating in a flock of sheep consisting of 900 breeding ewes (flock structure is given below).
He is interested in improving fleece weight via direct selection for the trait. The heritability (h2) and standard deviation (p) of fleece weight is 0.3 and 500 gms 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 rams: 3 3 Number of ewes: 180 180 180 180 180Explanation / Answer
1. What are the selected proportions of males and females?
Answer: proportion of male/female is 1/100
2. What is the overall generation interval?
Answer: Generation Interval is One year
3. What is the expected response to selection per generation?
Answer: Expected Response to selection is 54
4. What is the effective population size?
Answer: 23.8 is effective population size.
effective population size = (4N)m(N)f/(N)m + (N)f
=4 X 900 X 6/ 900+6
=23.8
note: answer only 4 due to chegg policy
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