The U.S. Department of Agriculture has confirmed the nation's third case of bovine spongiform encephalopathy -- mad cow disease.

Department of Agriculture Chief Veterinary Office John Clifford said initial testing from a cow on an unidentified Alabama farm had been inconclusive, but another test had returned positive results.

He said the cow had been buried on the farm and did not enter the animal or human food chains.

Scientists from the Food and Drug Administration, along with other federal and state officials, are investigating the origin of animal feed consumed by the infected cow, which had been on the Alabama farm for less than a year.

Cattle acquire the disease by eating feed contaminated with the remains of infected animals. Mad cow disease causes a fatal brain disorder in people who eat infected products from cattle.

The Agriculture Department said it was also attempting to locate other animals born in the same herd within one year of the affected animal.

"I want to emphasize that human and animal health in the United States are protected by a system of interlocking safeguards," added Clifford, "and we remain very confident in the safety of U.S. beef."

Copyright 2006 by United Press International