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How well do EBVs of young bulls predict the differences in performance of their progeny?

by Genetics editor Alex McDonald, 06 February 2018

THE outcomes of Cohort four of the Angus Sire Benchmarking Program (see today’s main story) show that the Estimated Breeding Values of the young bulls when selected for use in the ASBP did a very good job of predicting the differences in the average performance of their progeny.

The graph below shows the relationship between the EBVs for carcase weight of the young sires before being used in the ASBP Cohort Four, and the average carcase weight of their steer progeny when slaughtered. There is a strong relationship between the carcase weight EBVs of the young sires and the average carcase weight of their progeny.

Relationship between carcase weight progeny averages and EBVs for the ASBP Cohort 4 sires

The graph below shows the relationship between the Intra Muscular Fat percent (IMF%) of the young bulls when selected compared to the average MSA marbling score of the progeny when slaughtered at about 430kg carcase weight. Marbling score is strongly influenced by IMF% and this graph shows a very strong relationship between the IMF% EBV and the ultimate MSA marbling score of the progeny carcases hen slaughtered at about 430kg carcase weight.

Relationship between carcase weight progeny averages and EBVs for the ASBP Cohort 4 sires

The difference in the performance of progeny of individual sires are not always perfectly predicted by their EBVs as young sires, because the EBVs are only moderately accurate (70pc to 80pc) However the accuracy of selection is greatly enhanced when a group of young sires is selected (eg four young sires).

Once the progeny of a sire are evaluated the accuracy of the EBVs of that sire increase usually to over 90pc, so breeders can select progeny-tested sires (such as AI sires) with a high level of confidence that their EBVs will predict the differences in the performance of their progeny.

 



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