Tests on a second carcass, also red-flagged in preliminary testing as possibly being infected, were pending and would not be available for several days.

"The USDA remains confident in the safety of America's food supply," said John Clifford, deputy administrator of the department's Animal and Plant Health Inspection Service.

Clifford said tests by the federal laboratory at Ames, Iowa, on tissue from the carcass were negative.

"No further details, such as what type of animal, where the animal came from or what lab did the (initial) testing, would be disclosed," said Clifford.

In Canada, cattlemen said the announcement is good news and will ease some of the uncertainty surrounding the mad cow crisis.

"This is a good thing, as animal disease incidents are never a positive," said Canada Beef Export Federation president Ted Haney. However, he also warned the industry can expect more of the same.

"It is to be expected that there will be more announcements of this nature in the future," he said.

Alberta Beef Producers chairman Arno Doerksen agreed and encouraged cattlemen and consumers not to worry when suspected cases are announced.

Just because more BSE-contaminated cows -- or at least inconclusive tests -- will be discovered in North America, it does not mean Canadians have anything to fear, he said.

The testing measures the industry has adopted, in the wake of two BSE cases found within the last year, means testing is more thorough than ever, and any possible cases of the disease are being caught before they enter the food supply, said Doerksen.

"I don't think the fact that additional cases will be found should be a surprise," said Doerksen.

"With increased testing taking place, chances are there will be more cases."