WASHINGTON, Dec. 30 (UPI) -- The U.S. Department of Agriculture announced a series of sweeping changes in its mad cow surveillance and prevention programs Tuesday, some of which will take effect immediately.

"Today I am announcing steps we are taking to further protect our system," Agriculture Secretary Ann Veneman said during a news briefing. "In most instances, these actions are a result of work that was underway long before the discovery" of mad cows in Washington state last week and in Canada last May, Veneman said.

The changes include banning downer cattle from the human food supply and testing suspicious animals and holding them until test results are known. Beef from the cow that tested positive for mad cow disease on Dec. 23 in Mabton, Wash., was distributed for human consumption before the results had been returned.

In order to facilitate quick testing of the suspicious animals, the USDA also plans to implement so-called rapid tests, which the United Kingdom and several European countries began using after mad cow was detected in 180,000 cattle in Britain beginning in the 1980s.

"To have that kind of turnaround we would be going to one or potentially more of those (rapid) tests," said Ron DeHaven, USDA's chief veterinary officer.