The dental remains of the Alabama cow diagnosed with BSE turned out to be a lot easier to find than the cow's relatives, or even her origin. Announcing the end of its investigation in early May, USDA said it couldn't locate any of the cow's relatives, other than her last two offspring. A total of 36 farms and five auction houses were investigated.

“The investigation didn't reveal the BSE-positive animal's herd of origin. However, this was not entirely unexpected due to the age of the animal, along with its lack of identifying brands, tattoos and tags. Experience worldwide has shown that it's highly unusual to find BSE in more than one animal in a herd or in an affected animal's offspring,” said John Clifford, USDA Chief Veterinary Officer.

Dental records indicated the cow — she was non-ambulatory and was euthanized and buried at the owner's farm — was at least 10 years old. That means she was born before the ban on feeding ruminant protein was enacted.