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Virginia Cooperative Extension - Knowledge for the CommonWealth

Service sires for problem breeders

Dairy Pipeline: July 2001

Bennet Cassell
Extension Dairy Scientist,
Genetics and Management

What kind of selection standards should producers use for cows that are problem breeders? Several years ago, Dr. Ray Nebel and I published a study of nearly 300,000 services in Virginia herds. We wanted to know how producers answered that question. We found, for instance that the most sensitive issue to producers for repeat breeders was semen price. The amount spent for a unit of semen dropped by $2.77 from first to second service, by $2.44 from second to third service, and by another $2.07 for third to later services. Production and type characteristics declined as well, but not nearly as much as price. Many herds used young sires on second services as part of their commitment to progeny testing. The cow being bred mattered, too. Farmers spent more to breed the registered cow and the cow with higher production. Practices probably haven't changed much since that study. The May 2001 DHI herd summary sheet for the state showed that genetic merit of service sires changed very little from 1st to 2nd service, but did decline some for 3rd service cows. So, should sire selection standards change for repeat breeders? Remember that many cows that fail to settle are more unlucky than infertile. Don't be too quick to use a lower rated AI bull on second service cows. The statewide conception rate for second service, 39%, is lower than the 43% for first services. However, the odds of a conception on second service seem high enough to warrant use of a decent proven bull, though perhaps not the most expensive bull in the tank. State average conception continues to drop to 35% for third and later services. Perhaps a good pedigreed AI young sire would be a better choice for such cows. If you really want to raise a daughter of the cow you are breeding, a second service to a top bull is justified. It seems that most dairy farmers in Virginia are willing to use good proven bulls twice to get cows settled. The practice seems reasonable for continued genetic progress without undue waste of higher priced semen.

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