Bovine somatotropin use on dairy farms has increased.
According to the National Animal Health Monitoring System Dairy 2002 study, recombinant bovine Somatotropin (rbST) was being used by 15.2 percent of dairy herds in the 21 states studied.
A total of 22.3 percent of the cows were receiving the hormone.
Increased use. Since the Food and Drug Administration approved rbST in 1994, use on U.S. dairy farms has increased, especially on large operations.
Among large herds (500 or more cows), 54.4 percent used the hormone on one or more cows, while only 32.2 percent of medium herds (100-499 head) and 8.8 percent of small herds (less than 100 head) used the hormone.
The previous study in 1996 found that only 9.4 percent of all operations used rbST, and 38.7 percent of large herds were using it.
Yield increases. Proper use of rbST according to label prescribes administration at 14-day intervals starting eight to 10 weeks after calving. Proper use continues to result in a typical increase in milk yield of 10 pounds per cow per day as long as supplementation continues.
Repeated studies have demonstrated significant improvement in milk production while minimal adverse effects have been reported by producers and veterinarians.
Concerns? Some dairy producers have expressed concerns about the use of rbST, including animal health concerns, cost, and challenges associated with sorting cows and injecting them biweekly.
Other producer concerns include the intensive nutritional management and monitoring required and public health concerns.
Statistics. In herds using rbST in 2002, approximately 59.1 percent of cows received rbST during the current lactation. In 1996, 49.2 percent of cows in herds using rbST were receiving the hormone.
The Dairy 2002 study found that in herds using rbST, on average cows first received the hormone 81 days after calving and final treatment was received on day 270 after calving.
Regional use. The use of rbST was fairly uniform across the United States in 2002, with the exception of the West. In the Western region, 22.3 percent of dairy farms used rbST. The next highest region was the Midwest where 14.8 percent of the herds used the hormone.
In 1996, 15.2% of Western herds used rbST compared to 7.6 percent of Midwestern herds.
Regions were as follows: West – California, Colorado, Idaho, New Mexico, Texas, Washington; Midwest – Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, Wisconsin; Northeast – New York, Pennsylvania, Vermont; Southeast – Florida, Kentucky, Tennessee, Virginia.
Rolling herd averages. Herds with a rolling herd average (average pounds of milk per cow, per year) of more than 20,000 pounds use rbST at the highest percentage (32.4 percent of operations).
Only 8.6 percent of herds with a rolling herd average between 16,000 and 20,000 pounds used rbST.
Why not use it? Dairy producers who were not currently using rbST were asked to describe their reasons for not using the hormone. Responses varied between regions.
Cost and animal health were major reasons cited in all regions, but public health concerns were twice as prominent in the Northeast region as in any other region.
West and Southeast producers listed health of animals as the primary reason for not using rbST.
The Midwest and Northeast regions reported “other reasons” including personal beliefs, dairy plant regulations, or organic status as the principle reasons for not using rbST.
For more information visit www.aphis.usda.gov/vs.
(The author is an agricultural extension agent in Columbiana County. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)
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