You've reached the Virginia Cooperative Extension Newsletter Archive. These files cover more than ten years of newsletters posted on our old website (through April/May 2009), and are provided for historical purposes only. As such, they may contain out-of-date references and broken links.

To see our latest newsletters and current information, visit our website at

Newsletter Archive index:

Virginia Cooperative Extension - Knowledge for the CommonWealth

Increase the rank of proven AI bulls

Dairy Pipeline: February 2003

Bennet Cassell
Extension Dairy Scientist,
Genetics and Management
(540) 231-4762

DHI summaries for several years show that Virginia dairy producers breed about two thirds of their cows to proven bulls, 15 to 20% to AI sample sires, and the remainder to "other" bulls. The proven AI bulls used are at the middle of the pack, with an average rank for Net Merit of 50 to 60%. Herd bulls and low ranking AI sires both reduce genetic progress for lifetime economic merit. Producers have to control days open, labor for heat detection can always be used in other ways, high producing cows can be tough to get settled - there always seems to be a reason for some folks to have a bull around. While some natural service by some producers may be inevitable, it is difficult to understand why producers use AI bulls that rank between the 50th and 60th percentile. Almost HALF of the active AI bulls on the market are genetically better than the AI bulls used in current matings in Virginia DHI herds. The labor required to breed a cow to a low or high-ranking bull is the same. Semen prices are similar for superior bulls and lower ranking bulls if a little discretion is used. High-ranking bulls are routinely available, in large quantities through the AI studs that market semen in this state. The first step to address this problem is to be aware of where the bulls rank before the purchase. Check out the Virginia Tech Top Sire list at Bulls on that list are in the top 15% or so of all active AI bulls. We update it with each new sire summary, four times a year, so it is always current. Don't use the web? Ask your area dairy Extension agent for a copy, or call me. All it takes to solve the problem of low rank on service sires is to buy semen on bulls that are the current version of this list and then to use that semen immediately. Producers should take responsibility for the selection of service sires. Don't assume that a mating program will insure the use of better bulls - lots of Virginia herds rely completely on mating programs and the results cited above speak for themselves. It's up to the producer to use the top ranking bulls.

Visit Virginia Cooperative Extension