A South Korean retailer said it has stopped selling U.S. beef, one day after the U.S. Department of Agriculture confirmed a case of mad cow disease. USDA officials said the cow, infected with bovine spongiform encephalopathy in California, was never a risk to the food supply, CNN reported. South Korea is the second-largest importer of beef from the United States. The dairy cow in question was sent to the University of California, Davis, for initial testing, but the test was not conclusive. The USDA laboratory in Ames, Iowa, confirmed the cow had BSE. Dennis Luckey, executive director of Baker Commodities Inc., a rendering facility in Hanford, Calif., said the carcass was in quarantine Tuesday night. \"We\'re waiting now for USDA to tell us how to dispose of it,\" Luckey said.