A Wagga breeder uses natural mating in a flock of sheep consisting of 750 breedi

Question

A Wagga breeder uses natural mating in a flock of sheep consisting of 750 breeding ewes (flock structure is given below) Age when progeny are dropped: 2 3 4 5 6 Number of rams Number of ewes: 150 | 150 | 150 | 150 150 He is interested in improving fleece weight via direct selection for the trait. The heritability (h2) and standard deviation (op) of fleece weight is 0.4 and 1000 gms respectively. Assuming a weaning rate of 0.8 and no mortality, calculate 1. What are the selected proportions of males and females? (1 mark) 2. What is the overall generation interval? (1 mark) 3. What is the expected response to selection per generation? (1 markl) 4. What is the expected response per year? (1 mark) 5. What is the effective population size? (1 mark) 6 Whatis the rate ofng after 20 years?(L mark) 7. If instead of 12 rams, the breeder decided to only keep 6 rams, culling the rams after they have been used for breeding once (i.e. 6 rams of 2 years remain in the flock and there are no rams of 3 year age left), would the expected response increase or decrease and why? (1 mark) A table for selection intensity vales is available in resources section of the subject site. You can round up the selected proportions of males and females to the nearest 0.5% while looking up selection intensities. For example, in a breeding plan where the top 34.4% females are being selected-you can round this up to 35.5% to look up the selection intensity table.

Explanation / 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

5. What is the effective population size?

Answer: 47.2 is effective population size.

effective population size = (4N)m(N)f/(N)m + (N)f

=4 X 750 X 12/ 750+12

=47.2

note: answer only 4 due to chegg policy

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