The Bush administration has urged a federal appeals court to stop meatpackers from testing all their animals for mad cow disease. A skeptical judge questioned whether the government has that authority.

The government is seeking to reverse a lower court ruling allowing Kansas-based Creekstone Farms Premium Beef to conduct more comprehensive testing in order to satisfy demand from overseas customers.

Less than one percent of slaughtered cows are tested for the disease under Agriculture Department guidelines. The agency argued that widespread testing could result in a false positive that would scare consumers.

Creekstone attorney Russell Frye contended that the agency has no authority to prevent companies from using additional tests to reassure customers.

Larger meatpackers have opposed Creekstone's desire to use wider testing out of fear that consumer pressure would force them to begin testing all animals too. Increased testing would raise the price of meat by a few cents per pound.