The case of Mad Cow in California put a few South Korean retailers off of buying U.S. beef temporarily. But Canadian and Japanese importers haven't flinched.

For the first time in six years, a cow in the U.S. has tested for so-called mad cow disease. While officials say the dairy cow identified in California at no time entered the food supply, the price of cattle futures has moved sharply downward.

Two big South Korean retailers have pulled American beef off their shelves after a dairy cow here in California was found to have mad cow disease or BSE. It's the first case in the U.S. since 2006.