Use the top bulls while they are on top
Dairy Pipeline: April 2000
Extension Dairy Scientist
Genetics and Management
We all have a tendency to stay with what we like -- a comfortable chair, favorite sweaters, genes that fit. Some farmers like to continue to use certain AI bulls beyond the time when the bull can improve their herd. Every bull's genes are fixed at the moment of conception, but the genes of the other bulls available through AI keep getting better and better because of genetic progress. Young progeny tested AI bulls enter active service somewhere near the top of the active sire list, and stay in service as long as they are marketable. Sometimes, bulls remain marketable well beyond the time when they actually improve their progeny compared to bulls in AI service. Farmers may like the first few daughters they milked, the price may be right, reputation for conception might be good, or maybe farmers are just comfortable with a particular bull. A more progressive breeding program, however, uses bulls only while they rank near the top. Only rare bulls retain high ranking after four or five years of active service, and even those were probably under-evaluated on their first proofs. One good way to be sure that service sires rank high is to only buy semen from bulls in the top 20% or so of the active AI lineup. This method of choosing service sires doesn't choose bulls because they are a familiar, comfortable choice, but breeding programs should be about improved productivity. Save the "comfort" preferences for a pair of shoes that makes a long, hard day a little easier to take.