The genomic revolution is upon us. Has been for a while now. There’s no turning back, even if we wanted, to the days of yore when it took years to obtain enough data on a bull’s progeny to develop highly accurate EPDs.
But with this brave new genomics world come some concerns. One is that, with the speed that genomically-derived data can drive positive genetic change, it can also drive negative genetic direction with the same speed if wrong selection decisions are made. That’s a valid concern.
Based on that, recent research at the U.S. Meat Animal Research Center sheds some light on how we can best use production data in making genetic decisions.
The research looked at correlations between EPDs derived from single-step and multi-step genomic evaluations along with EPDs derived the old-fashioned way from non-genomically tested bulls. A very important point to keep in mind is that the non-genomic bulls were all high accuracy sires.
It’s also important to keep in mind that this is just one research project looking at an incredibly complex and diverse world that we’re still learning a whole lot about. So it’s important not to draw any definitive conclusions from these data. But it does give us something to think about.
One of the things coming from the research is that the multi-step genomic evaluation approach may have been overestimating differences in carcass data. “Because of these and other internal audits, Angus Genetics, Inc. adapted the SS (single-step) approach in their NCE (national cattle evaluation) and has been delivering weekly EPDs using this method since July 2017,” the research abstract says.
That’s good. Angus breeders can take comfort that their genomically-derived EPDs are more accurate.
According to Larry Kuehn, USMARC geneticist and lead researcher on the project, “The point is, less accuracy was obtained for some of the carcass traits where the sire accuracy was not as good.”
The research also indicated that regression between bulls tested with the single-step method and non-genomically tested, highly proven sires were similar for all traits.
Does that mean you shouldn’t consider genomically-enhanced EPDs in your bull buying decisions?
No, especially for yearling bulls. Genomically-enhanced EPDs on young bulls gives you greater accuracy than pedigree-developed EPDs. That’s because the accuracy gain with genomic tests on young bulls or heifers, where little or no data is available, is significant and diminishes greatly as the animal gets older and more progeny data is available.
But it does indicate, if genomically-enhanced EPDs aren’t available, you can rely on the old-fashioned EPDs, along with visual appraisal for important things like structural integrity, to be accurate enough to guide you in selecting the bulls that will move your herd in the direction you want it to go.