US prefers to manage for infertility
However, he admitted it could be the right thing to do in Ireland’s dairy industry, because it is based on lower cost seasonal milk production, mostly from grass.
He said changing breeding goals too quickly is unpopular with breeders, because they had been asked for years to breed for more milk and fat and protein, and their cattle are no longer as valuable after a new breeding goal is selected.
He said the global Holstein community knows that the fertility question must be addressed, but many are reporting positive trends without Ireland’s 35% fertility weighting in the EBI — which means a direct negative weighting for milk production, according to Dr Lawlor. In the US, fertility gets only a 19% weighting, and he recommended management or feeding changes as better solutions to infertility, which is only 4% heritable. But there are big fertility differences between bulls to take advantage of, he pointed out.
Dr Lawlor said US farmers aim to replace between 25% and 35% of their cows annually, and their ideal is a 33% annual turnover of cows, in order to have rapid genetic progress and younger trouble-free cows to work with. Only at about 40% turnover does cow replacement become a big problem.
