A breeder uses natural mating in a closed stud consisting of 375 breeding cows (
ID: 3302954 • Letter: A
Question
A breeder uses natural mating in a closed stud consisting of 375 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?
The Questions relate to chi-square analysis of genetic problems; and response to genetic selection.
PLEASE SHOW YOUR WORKING
A table for selection intensity vales is available. 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.
Age when progeny are dropped: 2 3 4 5 6 Number of bulls: 1 1 Number of cows: 75 75 75 75 75 ity 2 6 0 5 1 8 5 2 0 9 8 8 7 8 8 9 1 2 4 6 8 1 4 6 036048 887 0407405 297 0853197532086 111100000099 26296533334680359269 185307 6354522 25827 12356 8261605050 5296 111100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -o-o-o-o-o-o-1 le 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 5667789 33518781495 977 1988 852 se nt 222222222222222222222 1 % cte 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 024680 05050505050 5566778899 123456789 1 1 33333333333322222222 69818804087779260506 63247297666 .7 5 4 3 2 2 1 1 1 0 0 .9 9 9 8 8 8 7 7 7 7 7 6 6 6 6 6 6 5 5 32222222222222222222 55544443333 5678 0000000000 00000000000000000000 00000000001Explanation / Answer
The generation interval is the average age of parents at the birth of progenies (Gi).
Calculation for the effective population size structure below (denoted as Eps)
Eps= 75x5+2=327
Gif= 2x75+3X75+4X75+5X75+6X75/75+75+75+75+75
=150+225+300+375+450/375
= 1500/375
= 4
Generation interval= Sr= (Im+If/GIm+Gif) h2p
= (Im+If/GIm+Gif)h2a
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