Dairylink Ireland participants with autumn-calving herds are currently finalising sires for use in the upcoming winter breeding season.

Several programme participants are selecting bulls with high PTAs for butterfat, protein and fertility.

These farmers are not focusing primarily on a high requirement for milk PTA as this could exclude a lot of bulls that have the potential to lift milk components and improve fertility.

This is not a major issue for Dairylink farmers as their cows already have plenty of genetic potential to deliver high yields. Indeed, focusing on breeding for better fertility, and not milk volume, will be a more effective way of increasing annual milk yields per cow.

“If you are going to improve variables like butterfat, protein and fertility, you need to select for them quite aggressively to make any significant in-roads,” said Dairylink adviser Aidan Cushnahan.

Selection criteria

Aidan has drawn up selection criteria for programme farmers to apply when choosing bulls. When picking bulls from the PLI list, the PTAs for butterfat and protein should be at least +0.08% each, and the fertility index should be at least five days.

Aidan has also included a requirement for at least 100kg for the PTA for milk. This has been set relatively low as it allows the best bulls for milk components and fertility to remain in the mix. There are over 70 Holstein bulls in the PLI system which meet Aidan’s minimum criteria for all four traits.

Dairylink farmers are also assessing bulls which are list under the Irish Estimated Breeding Index (EBI) system. Aidan’s suggested criteria under EBI is for bulls to have milk between zero and 200, butterfat of at least +0.15%, protein of at least +0.10% and a fertility sub index above €100.