WASHINGTON (AP) -- The Bush administration on Friday urged a federal appeals court to stop meatpackers from testing all their animals for mad cow disease, but a skeptical judge questioned whether the government has that authority.

The government seeks to reverse a lower court ruling that allowed Arkansas City, Kan.-based Creekstone Farms Premium Beef to conduct more comprehensive testing to satisfy demand from overseas customers in Japan and elsewhere.

Less than 1 percent of slaughtered cows are currently tested for the disease under Agriculture Department guidelines. The agency argues that more widespread testing does not guarantee food safety and could result in a false positive that scares consumers.

"They want to create false assurances," Justice Department attorney Eric Flesig-Greene told a three-judge panel of the U.S. Court of Appeals for the D.C. Circuit.

But Creekstone attorney Russell Frye contended the Agriculture Department's regulations covering the treatment of domestic animals contain no prohibition against an individual company testing for mad cow disease, since the test is conducted only after a cow is slaughtered. He said the agency has no authority to prevent companies from using the test to reassure customers.

"This is the government telling the consumers, `You're not entitled to this information,'" Frye said.

Chief Judge David B. Sentelle seemed to agree with Creekstone's contention that the additional testing would not interfere with agency regulations governing the treatment of animals.

"All they want to do is create information," Sentelle said, noting that it's up to consumers to decide how to interpret the information.

Larger meatpackers have opposed Creekstone's push to allow 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.

Mad cow disease, or bovine spongiform encephalopathy, can be fatal to humans who eat tainted beef. Three cases of mad cow disease have been discovered in the U.S. since 2003.

The district court's ruling last year in favor of Creekstone was supposed to take effect June 1, 2007, but the Agriculture Department's appeal has delayed the testing so far.

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