Young Bull EBVs in Sale Catalogues

Bull Sale Catalogues list EBVs for a set of traits for each bull, together with accuracies for each trait.  Clearly higher accuracy is desirable as it suggests a more reliable estimate of genetic merit for that trait and that bull.  Young bulls without progeny will naturally have lower accuracy EBVs than older bulls with measured progeny.

For example, in the Angus Sire Benchmarking Program starting EBVs (likely catalogue EBVs) for birthweight were:

Highest ten Birthweight EBV Bulls = +6.2 Kg and 75% accuracy at start.

Lowest ten Birthweight EBV Bulls = +2.8Kg and 78% accuracy at start.

After many progeny were measured over several years and actual birthweights contributed to new “final” BW EBVs, the new BW EBVs were:

Highest ten Birthweight EBV bulls = +6.6 Kg and 94% accuracy at finish.

Lowest ten Birthweight EBV bulls = + 2.8 Kg and 95% accuracy at finish.

Although the EBV rankings of some individual bulls did vary a little, overall the lower accuracy EBV of the young bulls was still a good predictor of later performance. Similar results were shown for the range of other EBVs.

Take Home Message

Catalogue EBVs are the best guide you can get to the likely genetic performance of your new bulls.  In the above example, bulls destined for heifer joining from the low group (BW EBV +2.8Kg) are likely to cause fewer calving difficulties than the heavier calves from the high group (BW EBV +6.6Kg), despite low starting/young accuracies.

Source:  Edited from Angus Australia: