Suspect mad cow was free of BSE

An animal suspected last week of having mad cow disease proved to be free of infection, the U.S. Agriculture Department said yesterday.

The USDA reported the country’s first case of the disease in December, and stepped-up testing has since turned up three “inconclusive” cases that later turned out to be false alarms.

“The USDA National Veterinary Services Laboratories in Ames, Iowa, has determined that the inconclusive screening test sample reported on November 18 has tested negative for BSE upon confirmatory testing,” said John Clifford, deputy administrator at USDA’s Animal and Plant Health Inspection Service.

Mad cow disease, officially known as bovine spongiform encephalopathy, or BSE, is a fatal disorder that attacks the central nervous system of cattle. A form of it has infected humans who eat diseased tissue, though no known cases have been contracted in the United States.

Ranchers and meat packers braced for the worst, but were relieved to hear the negative result.

“This is not an unexpected situation and proves why it is important to await the final test results from USDA’s National Veterinary Services Laboratory,” said Jan Lyons, president of the National Cattlemen’s Beef Association, a trade group for ranchers.

The false positives initially sent markets tumbling, but they recovered ahead of yesterday’s announcement.

“It creates a lot of volatility in the market. There is a pause, restlessness, fluctuation, then things simmered down,” said Chuck Levitt, senior livestock analyst at Alaron Trading Corp. in Chicago.

Cattle futures climbed on speculation that the final test result would be negative, and forecasts indicating that the beef supply might be tightening. Futures for February delivery increased 1.9 cents, or 2.2 percent, to 87.85 cents a pound on the Chicago Mercantile Exchange.

Animal health inspectors discovered the country’s first, and so far only, confirmed case of the disease in December in a Washington state dairy cow.

Since the December case, the USDA has instituted new safeguards to keep infected animals and the tissue most likely to transmit the disease out of the food supply.

Since June 1, the USDA has tested 121,000 animals. The agency plans to screen as many as 268,000 animals in a 12- to 18-month period. There were 103.6 million cattle in the United States as of July 1, according to the National Agricultural Statistics Service.

A panel convened by the USDA earlier this year found that animals infected with mad cow likely were imported into the country from Canada and Europe in the 1980s and 1990s, and some indigenous cases are likely.

“These animals have not been detected and therefore infective material has likely been rendered, fed to cattle, and amplified within the cattle population, so that cattle in the USA have also been indigenously infected,” the panel’s report said.