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AI Bulls Are the Best Choice for Genetic Improvement

Dairy Pipeline: December 1999

Bennet Cassell
Extension Dairy Scientist, Genetics and Mangement
Virginia Tech
(540) 231-4762

Some stories are worth retelling. AI bulls are better than non-AI bulls. Each time USDA publishes new genetic evaluations, as they just have in November, the researchers publish a table comparing bulls in AI with non-AI bulls. Some of the averages are in the table below. Only bulls receiving their first evaluation in November 1999 are included.

 Bulls receiving first evaluations in November 1999
AI bullsNon-AI bulls
    Number of bulls387432
    PTA milk (lbs.)1525712
    PTA productive life (mo.)1.20.5
    Number of bulls34 35
    PTA milk (lbs.)1216732
    PTA productive life (mo.)1.41.1

Genetic evaluations for milk are higher for AI bulls by 813 lbs. in Holsteins and 484 lbs. in Jerseys. Most producers would not be surprised by that result, but the comparison of productive life evaluations may be news. Daughters of AI bulls last longer than daughters of non-AI bulls do, particularly in the Holstein breed. I have heard several producers through the years tell me that "my best cow was by a herd bull," concluding that AI bulls offer no advantage. In almost all cases, that one favorite cow was a unique remnant of a large group of daughters of some herd bull, most of which were culled and forgotten long ago. AI bulls are the best opportunity dairy farmers have to improve economic efficiency of their cows. There is a difference between the herd bull and an AI bull, and today's competitive dairy economy makes the AI kind more valuable than ever to producers who intend to remain competitive.

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