WASHINGTON (AP) - Animal feed producers are doing a little better at following rules intended to keep mad cow disease out of the United States after warnings the government would crack down on violators.

The Food and Drug Administration reported Friday that of 157 feed companies it reinspected after issuing the stern warning in January, only one continued to violate the rules.

That doesn't mean the problem is solved - the FDA still has more than 1,000 companies to inspect, and first-time inspections show hundreds of companies still violate the rules.

But the reinspections show ``people are beginning to take this much more seriously,'' said FDA's Dr. Murray Lumpkin.

The food supply remains safe despite the violations because no cases of mad cow disease have been found in U.S. cattle, the FDA said. But if the deadly brain disease does sneak into the country, companies that don't follow the agency's rules could spread it through animal feed.

Animals can get the disease by eating the tissue of other infected animals. Thus, the FDA bans any proteins from cows, sheep, goats, deer or elk - animals that get similar brain-wasting diseases - from feed for cows, sheep or goats. Poultry or pigs can still eat those proteins, but feed must be labeled ``do not feed to cows or other ruminants'' and companies must have systems to prevent accidentally mixing up the feeds.

McDonald's Corp. has given its meat suppliers until April 1 to certify that the cattle they buy were fed in accordance to FDA regulations. Now, meatpackers, cattle producers and feed mills are all developing certification programs designed to show they are in compliance with the rules.

FDA outlawed the feeding of mammalian meat and bone meal to cattle, sheep and goats in 1997 and imposed a series of rules to ensure that feed mills comply with the ban. The feed regulations are designed to keep mad cow disease, known formally as bovine spongiform encephalopathy, from spreading if it ever reaches this country. The disease has devastated the beef industry in Europe but has not been found in the United States.

The latest FDA inspections found:

-Of 177 renderers - companies that turn slaughtered animals' parts into meat and bone meal - that handle risky feed, 14 percent had no system to prevent feed mixups and 4 percent lacked warning labels. That's better than January inspections that found more than one-quarter of such firms in violation.

-Of 397 FDA-licensed feed mills that handle risky feed, 15 percent lacked warning labels and 13 percent lacked mixup-prevention systems, about the same as the agency found in January.

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