homework ch 10

homework ch 10 - own BV. You practice trunication selection...

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Sametra Williams November 15, 2008 ANSC 4018 Chapter 10 HWK 10-1: -.088 lb/ year 10-2: a. .06/.22= 27% b. Heritability accuracy of selection 10-3: a. The breeder is selecting a random sample of ewes produce twins. She is therefore selecting from the top 36%. Effective proportion saved is then .36 and selection intensity is 1.04 standard deviations. b. Effective proportion is .56 and selection intensity is .71 standard deviations. c. Improved management caused a greater proportion of ewes to have twins. The breeder cannot now distinguish between 36% and 20% under improved conditions. She must select from the top 56% rather than the top 36% because it is a less intense selction. 10-4: a. If she picks the top 35% she has to choose from 20% produce twins and 65% produce singles. Effective proportion (P[e]) is 85% or .85; i= .275, genetic progress is lower. b. No, because she lowered selection intensity. c. Trait is continuously expressed so you can truly select the top 35%. If it is a threshold trait you pick out of all the pregnant ones because each individual ewe will have their
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Unformatted text preview: own BV. You practice trunication selection by saving the top 35% and your i=1.06. 10-5: a. 211 lb/yr b. 214 lb/yr c. Requiring dams of future sires to have an additional lactation record results in slightly faster genetic gain. Increased accuracy of selection outweighs the benefit of a shorter generation interval for this path. Realistically, however, the difference in results between the two programs is negligible. 10-6: a. 14.08 lb/yr b. 2 nd strategy is higher and causes the greatest change in yearling weight. c. Selection intensity: went from 1.4 to 6.4 you cut intensity by more than 50%. 10-7: 7.9 lb/yr 10-8: a. 3.0 b. 6.0 c. You will be behind because of where you started. You are going to have to buy high quality females. You started with a lower level cattle than he did. Overall, it depends on where you started from and how far behind you are/were....
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