WASHINGTON - No sign of mad cow disease was found in an animal the Agriculture Department had singled out for followup tests, officials said Tuesday. Initial screenings last week had raised the possibility of a new case of the disease in the United States. 
 
A more definitive test at the National Veterinary Services Laboratory in Ames, Iowa, came back negative, the officials said. The announcement was a relief to the U.S. beef industry, which is still trying to recover from the nation's first case of the disease last December. 

The department said it ran a "gold standard" test twice. Officials did not say where the cow came from or why it was suspected of being diseased. 

"Negative results from both ... tests make us confident that the animal in question is indeed negative," the announcement said. 

The initial screenings had produced what officials said were "inconclusive" results, but just the possibility of a second case had rattled cattle producers, meatpackers and hamburger chains. 

Julie Quick, an Agriculture spokeswoman, said the department would provide no further information about the suspect cow since the test results came back negative.