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Virginia Cooperative Extension - Knowledge for the CommonWealth

Make better use of top AI bulls

Dairy Pipeline: September 2002

Bennet Cassell
Extension Dairy Scientist,
Genetics and Management

According to our July 2002 state DHI summary, the average Net Merit of AI service sires in Virginia is $375. A Holstein bull with that evaluation ranks at the 62nd percentile - over one third of the active AI bulls on the market are better. This is a little pessimistic, because a few of those matings (well under 10%) are not Holstein, but the question remains: If you're going to go to all the trouble of AI, why not use a better bull? Better bulls are readily available and affordable in our area through regular marketing services. Obviously, something is happening to cause rank of service sires to be this low. When I looked back one year to July 2001, the average Net Merit was $343, which would have ranked at the 53rd percentile by today's standards. If Virginia producers simply left today's semen inventory sit in the tank and used it next year, the rank of those service sires do the same thing - drop from the 62nd to about the 53rd percentile. Maybe something like that is really happening. It just doesn't make any sense that a dairy farmer would skip a third of the way down an active AI list to buy semen - but a producer might decide to use a higher ranking bull and delay either the purchase or the use of that semen for a couple of years or more before calves are born. If that is happening in your herd, then you aren't getting as much advantage out of your semen investment as you should. I offer two simple suggestions. First, make sire selection decisions (using a up-to-date list of bulls) AND buy the semen at the same time. I'm assuming here that you'll buy near the top of the list - don't let me down on that one! Second, start breeding cows to that semen right away. If you have an inventory of semen from "old" sire selection decisions, either discard it (most won't) or use it on problem breeders (which is quite a bit like discarding it). At least start by breeding some of your most fertile animals to bulls that rank well above the 80th percentile on the day you use them. And get that old semen used up! We really shouldn't sacrifice the opportunity to milk cows with better genetics by hesitating on high ranking, newly proven AI bulls.

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