Dairy farmers face a decision these days about how heavily to use young bulls with exceptional genomic proofs in herd breeding programs. Scientists from AIPL conducted a study that compared selection on proofs with and without genomic information on Holstein bulls with and without daughters. The table below shows the results.
Production records were restricted to those available in 2004. Proofs were calculated with and without genomic information on young bulls and bulls with daughters. The best 20 young bulls with and without genomics and the best 20 proven bulls, with and without genomics were chosen. Then, all the data available through January 2009 were used for proofs and the four selected groups were compared. In those five years, the young bulls received progeny test results and proven bulls gained second crop daughters. The BEST group of 20 bulls was the group of young sires chosen on genomic evaluations, and second best, $53 behind the best group, was the group of proven bulls with genomic data. This test is like looking back to selection decisions made five years ago to see how well the proofs held up and those young bulls with genomic proofs were the best choice. But the table also shows that the young bulls’ proofs declined an average of $130 over those five years. The most stable proofs were on the top 20 proven bulls based on genomic proofs with only a $30 drop. The first conclusion from this study is that farmers should use a group of young bulls with outstanding genomic evaluations heavily, in place of many proven bulls, but we can’t expect to find the very best of large groups of young bulls without progeny tests. A second conclusion is that genomic proofs on top proven bulls hold up better over time than they used to. Farmers can use those individuals more heavily than in the past.
|Select the best 20 Holstein bulls based on 2004 information||Average Net Merit based on data available in 2009||Change in Net Merit from proofs based on 2004 data|
|Young bulls with traditional Parent Average evaluations||$395||-$278|
|Young bulls with genomic evaluations||$516||-$130|
|Proven bulls, traditional PTA||$381||-$96|
|Proven bulls, genomic PTA||$463||-$30|