If the Alabama animal was about 10 years old, it would have been born before the 1997 ban on cattle feed made from rendered cattle parts, which scientists believe is the major way BSE is transmitted between animals. Officials said they were trying to track its original herd to test cattle of similar age.

But the weekend discovery of a bone shard in what was supposed to be a boneless, boxed beef shipment to Hong Kong might prove a bigger headache in restarting sales to the rule-conscious Japanese, said Steve Kay, editor of the Petaluma, Calif.-based Cattle Buyers Weekly. Hong Kong suspended purchases from the Swift's Greeley, Colo., plant that shipped the beef on Saturday.

On Jan. 19, Japan halted US beef imports after a New York company shipped prohibited bone-in cuts of veal, just five weeks after a two-year ban was lifted. American producers originally lost the $1.4 billion Japanese market after the December 2003 discovery of the first case of the brain-wasting disease, bovine spongiform encephalopathy.

Did Not Enter Food Chain

The latest case involves a downer, or nonambulatory, cow that was euthanized after a local veterinarian took tissue samples, which twice proved inconclusive at a Georgia laboratory.

A more accurate Western blot test at the National Veterinary Services Laboratory in Ames, Iowa, proved positive for BSE, said Dr. John Clifford, the US Agriculture Department's top veterinarian.

"The animal was buried on the farm and did not enter the animal or human food chains," Clifford told a teleconference with reporters. He declined to identify the operation or its location. Federal officials normally withhold the name of owners of infected cattle to ensure the cooperation of cattle and dairy producers.

Born Before 1997 Feed Ban?

Alabama Agriculture Commissioner Ron Sparks told The Associated Press that information on the farm would not be released until his agency's investigation was completed in the next few days.

The cow had been on the farm less than a year, Clifford said.

It was identified as a Santa Gertrudis, a breed developed from Shorthorn and Brahman cattle nearly a century ago by Texas' legendary King Ranch to thrive on arid range.

If the Alabama animal was about 10 years old, it would have been born before the 1997 ban on cattle feed made from rendered cattle parts, which scientists believe is the major way BSE is transmitted between animals. Officials said they were trying to track its original herd to test cattle of similar age.

Bottom Line: Beef Is Safe

The case underscores the urgency for a national animal identification system, said Kay. The United States trails Canada, Japan and the European Union, which already operate mandatory programs.

The National Beef Cattlemen's Beef Association stressed that the infected cow never entered the food supply.

"The bottom line for consumers remains the same: Your beef is safe," said Terry Stokes, the group's chief executive.

But the Humane Society of the United States said the case should prompt the government to make permanent its temporary ban on slaughtering downer cattle.