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Service Sires for Problem Breeders

Dairy Pipeline: February 1998

by Bennet Cassell
Extension Dairy Scientist, Genetics and Management
540/231-4762 email:
Virginia Tech

The herd summary sheet from DRMS Raleigh includes a section showing the number of first, second, third and later, and total services for the herd. The section also lists percent successful services and service sire PTA$ for each category. State average figures (Dec 97) showed that service sires used on first service averaged $186, $7 higher that the bulls used on third and greater service, but only $1 higher than bulls used on second service. What should those numbers be? As a geneticist, I could simply say "Higher!", but the reality of herd management asks a different question. How much should herds spend on semen for the problem breeder? Several years ago, Dr. Nebel and I did a study of nearly 300,000 services in Virginia herds which examined more than just service sire PTA$. We found, for instance that the most sensitive issue to producers for repeat breeders was semen price. The amount spent dropped by $2.77 from first to second service, $2.44 from second to third service, and another $2.07 for third to later services. Production and type characteristics dropped 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. What should the numbers on the DHI form 202 look like? Don't be too quick to hold off on top proven bulls on second service cows. Many cows that repeat aren't subfertile, they're just unlucky. The conception rate for second service is 43% compared to 45% for first service cows state wide. Conception does drop to 38% for third and later services and good pedigreed AI young sires could be a better choice for such cows. As our study several years ago showed, farmers also considered the cow and it makes sense. If you really want more cows like the cow you are breeding, an extra service to a top bull seems justified. However, for any cow that is good enough to raise her daughter, the better the service sire, the better the calf has a chance to be. State averages suggest that most farmers 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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