BIOL 2400 Lecture Notes - Lecture 2: Fecundity
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A genetic evaluation report for terminal sire breeds for 2007 is shown below. The sires in the report were all born in 2005.
The report shows the estimated breeding values (EBVs) for various traits calculated using BLUP, the accuracy associated with these EBVs and a âCarcase Plusâ index value for 5 animals. The objective of the âCarcase Plusâ index is to increase post-weaning weight, increase post-weaning eye muscle depth and decrease post-weaning fat depth. The table below also gives the average EBV and index values for all animals born in 2005
5
Animal | Post- weaning weight Post- weaning fat depth Post- weaning eye muscle depth No. of lambs weaned Post- weaning faecal egg count | Carcase Plus Index |
Sire 1 | 11.7 -0.5 0.4 3 -23 69% 70% 71% 42% 45% | 170 |
Sire2 | 7 -1.6 1.7 -10 14 68% 66% 71% 40% 36% | 170 |
Sire 3 | 10.9 -0.2 0.7 3 -35 65% 63% 68% 38% 56% | 163 |
Sire 4 | 12.6 -1.9 -0.6 1 10 67% 64% 69% 39% 58% | 185 |
Sire 5 | 9.6 -0.6 2.2 2 0 39% 37% 41% 10% 28% | 176 |
Mean of 2005 born lambs | 7.1 -0.6 0.4 5 0 | 147 |
a. Sires 1 and 2 have the same âCarcase Plusâ index value of 170 but different values for the component trait EBVs (Post-weaning weight, post-weaning eye muscle depth and post-weaning fat). Explain how this can be the case.
b. Assume a new index was created called âCarcase Plus-FECâ. The âCarcase Plus- FECâ index is based on EBVs for post-weaning weight, muscle and fat (as âCarcase Plusâ index) but also includes EBVs for post-weaning faecal egg counts. Would you expect a change in the ranking of animals when ranked on this index? Explain your answer commenting on the magnitude of re-ranking for specific index comparisons.
c. What is the expected difference in progeny post-weaning weight if Sire 3 was selected compared to an average 2005 born animal?
d. Give a likely reason why the accuracies associated with post weaning weight EBVs are generally higher than accuracies associated with EBVs for the number of lambs weaned.
e. Briefly explain what information may have been used in calculation of the post weaning weight EBVs for these sires.