3/15/99

Contacts:
Jeffrey Berger, Animal Science, (515) 294-3435
Brian Meyer, Agriculture Information, (515) 294-0706

HOLSTEIN STILLBIRTHS RISE, BUT GENETIC LINK NOT YET ESTABLISHED

DES MOINES, Iowa -- Even though the incidence of stillbirths in Holstein dairy herds in the United States has increased since the mid-1980s, there is still little evidence it is a genetic trend, say Iowa State University researchers.

"The genetic issue is still an open question," said Jeffrey Berger, a professor of animal science. "Stillbirths are not a black-and-white issue. There may be many factors involved related to management, nutrition and environment."

Berger and graduate student Christy Meyer presented results of his research at the Midwest meetings of the American Society of Animal Science and American Dairy Science Association, March 15-17 in Des Moines.

Stillbirths, which are defined as calves that die within 48 hours after birth, cause an estimated loss of $132 million each year to the U.S. dairy industry.

Stillbirths also may be an important issue for U.S. exports. The Swedish dairy industry has reported increases in the number of stillbirths, and have questioned whether it is related to imports of semen from American Holstein bulls. Some countries, including Sweden, limit the amount of semen that can be imported each year from any one bull if the animal does not have a genetic evaluation for stillbirths.

"Currently, our research does not support the development of genetic evaluations for stillbirths," Berger said. "We feel a more important trait to focus on, and perhaps a better way to approach the stillbirth problem, is by addressing dystocia -- difficult calvings in which cows require help from farmers or veterinarians to give birth."

Berger and Meyer studied stillbirth information from a national database on calf births that is compiled by ISU each year. The database includes information on stillbirths, calving ease and other factors. They analyzed records of 613,808 Holstein births from 1984 to 1996. Roughly one-fourth of the births were calves born to heifers. The rest were births to older cows.

In 1984, stillbirths accounted for 4 percent of calves born to the older cows. In 1996, that percentage had risen to 7 percent. In 1984, stillbirths totaled 8 percent of calves born to Holstein heifers. In 1996, that percentage was 14 percent.

"The increasing trend in stillbirths is clear, but there's not yet good evidence that it's genetically determined," Berger said. "Right now, the evidence comes back to dystocia. There is some debate whether stillbirth and dystocia are different traits. There is good evidence suggesting they are different. We believe dystocia is where attention must be paid. It may be that improved management and more careful attention to calving will help solve the problem."

Berger continues research into the genetic question. Using the national dystocia database, he is working to find any genetic links between bulls and stillbirths in their progeny. "The result will help determine if there are sires or sire families with a high liability for stillbirths," he said. "If there is a link, it could be used to develop ways to better select artificial insemination sires."

Collaborating with Berger and Meyer are researchers from the National Association of Animal Breeders and Genex Cooperative Inc., an artificial insemination firm. The National Association of Animal Breeders funds the work.

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