A new Food and Drug Administration  (FDA) report has revealed that hundreds of animal feed producers have violated regulations meant to keep mad cow disease out of the country.

The FDA are keen to stress that the violations do not mean the food supply was tainted, however, and as yet no cases of mad cow disease have been found in the US.

The FDA inspections found that of 180 renderers (companies that turn slaughtered animal parts into meat and bone meal) that handle risky feed, 16% lacked warning labels and 28% had no system to prevent feed mix-ups.

The FDA is warning that companies could face seizures, shutdowns and prosecution if they continue to violate rules meant to keep American livestock from eating slaughtered-animal parts, a process many believe to be the cause of BSE, linked to the deadly human brain disease vCJD.

FDA veterinary chief Dr. Stephen Sundlof promised more intense inspections to ensure that the rules are properly enforced.