The government will close a gap in the U.S. defense against the spread of mad cow disease (search) by changing feed regulations to mirror those in Canada, FDA commissioner Lester M. Crawford said Monday.

In remarks to a food policy conference hosted by the Consumer Federation of America (search), Crawford said the new regulations would be coming soon. But did not say when.

Canada has proposed regulations banning at-risk tissues — brains, spinal cords and other parts that can carry mad cow disease — from feed for all animals, including chickens, pigs and pets. The new rules have not yet taken effect; current rules are the same as U.S. rules.

Ground-up cattle remains — leftovers from slaughtering operations — were used as protein in cattle feed until 1997, when a mad cow outbreak in Britain prompted the U.S. to ban the feed industry from using cattle remains in cattle feed.

However, the U.S. ban doesn't apply to feed for other animals, creating a potential pathway for the mad cow protein to be fed back to cattle.

For example, it's legal to add cattle protein to chicken feed. Feed that spills from cages mixes with chicken waste on the ground, then is swept up for use in cattle feed. Besides the risk of transmission from uneaten feed, scientists believe chicken waste presents a risk because the BSE protein will survive the trip through a chicken's gut.

The FDA promised to tighten the rules after the nation's first case of mad cow disease was confirmed in December 2003. FDA said it would ban blood, poultry litter and restaurant plate waste — all potential pathways for the mad cow protein to be fed back to cattle.

FDA scrapped those restrictions last July. At the time, Crawford said an international team of experts assembled by the Agriculture Department was calling for even stronger rules and that FDA would produce new restrictions in line with those recommendations.

The first U.S. case of mad cow disease, confirmed in December 2003, was in a Canadian-born cow in Washington state. The second case, a Texas-born cow, tested positive in June.

Crawford did not say whether the new regulations would ban cattle blood and restaurant leftovers, also considered potential pathways for BSE (search), from cattle feed.

"Our regulations will mimic theirs," he said.