WASHINGTON (AP) – Government officials were trying Friday to trace a cow shipped to the United States from the same Canadian herd as an animal infected with mad cow disease, yet officials said it was unlikely the imported cow had been infected.

Canada announced a case of mad cow disease on Sunday, days after the Bush administration said it would lift a U.S. ban on Canadian cattle.

The infected dairy cow was 8 years old and from Alberta. It was born in the same herd, within one year, of a cow shipped to the United States in February 2002 for immediate slaughter, the Agriculture Department said.

“USDA believes it is extremely unlikely that this imported cow would have been infected,” said Ron DeHaven, administrator for the agency’s Animal and Plant Health Inspection Service.

Nonetheless, DeHaven said, the department is making “every reasonable effort to obtain and provide information about the disposition of this animal as well as any other birth cohorts that are traced to the United States through Canada’s epidemiological investigation.”

In May 2003, when the first Canadian cow tested positive for mad cow disease, officials traced a small number of animals from the same herd to the United States.

American cattle producers said the government’s announcement confirms their belief that Canadian cattle imports should not resume as scheduled on March 7.

“It further demonstrates that USDA is dangerously premature in issuing this final rule,” said Bill Bullard, chief executive officer of R-CALF United Stockgrowers of America.

Sen. Kent Conrad, D-N.D., questioned whether Canada is enforcing a ban on use of cattle remains in cattle feed, which regulators say is the best way of preventing the disease’s spread.

“All of us have to hope that this animal is not contaminated, it’s not sick, and it’s not entered the food chain,” Conrad said. “But what this is telling us is that there’s a real risk. We’ve got a series of red flags. We ought to pay attention. The consequences of a failure to get this right are just too great.”

Mad cow disease is the common name for bovine spongiform encephalopathy, or BSE. People who eat tainted meat can contract a fatal brain disease called variant Creutzfeldt-Jakob disease.

More than 170,000 U.S. animals have been tested for the disease since officials discovered the lone U.S. case of mad cow disease in Washington state in December 2003. That animal also was imported from Canada.