January 2, 2004 USA TODAY by Elizabeth Weise

In an effort to safeguard the beef supply against mad cow disease, the U.S. Department of Agriculture (USDA) on Tuesday announced an immediate halt to the practice of slaughtering for human consumption any sick or injured cows that cannot walk. The Washington state Holstein found Dec. 23 to be infected with mad cow disease had been a downer.

Chandler Keys of the National Cattlemen's Beef Association says the 150,000 to 200,000 downers a year are a fraction of the 35 million U.S. cattle slaughtered each year. But animal experts say the ban will force changes in the industry. Temple Grandin, professor of animal science at Colorado State University, believes 90% of downer cases are preventable.

An estimated 3% to 4% of beef cattle are downers. But research in Wisconsin and Minnesota in 2003 found that 23% of dairy cattle were lame. Dairy cattle are more likely to become downers in part because they live longer, says Dan Weary, an expert on dairy cow lameness at the University of British Columbia. Beef cattle are slaughtered in their prime.

A small number of bad dairies push cows beyond their physical and genetic limits, Grandin says. Heifers are forced to mature so fast that their bones don't have time to lay down enough calcium, creating leg problems and lameness, she says. Cows are pushed to increase their milk supply "until they're pouring their bones into the milk pail," says Grandin.

The Washington state Holstein with mad cow disease was a downer because of paralysis from calving injuries. That can happen to cows when their calves are too big, often a result of bad breeding practices.

Using genetic information about bulls, dairies can easily select for smaller calf size, says Karen Jordan, a dairy veterinarian in Siler City, N.C.

Jordan says the economics of a no-downer policy will push all cattle owners to send animals to slaughter sooner, before they become downers. A healthy dairy cow produces about $ 2,000 worth of milk a year, she says. A downer cow typically brought $ 250 to $ 300 at slaughter. Sending an animal to a rendering plant costs the owner $ 20 to $ 50 per carcass, she says.

Now, "every time you look at a cow that's lying down, you know that's the end -- there's no income from that animal," she says. "It's going to cause the industry to work harder to prevent any animal from ever even thinking about becoming a downer."

One positive effect of the ban is that it might reduce other illnesses as well. A USDA study published in August found that downer cows had three times more of the deadly bacterium E. coli 015H7 than other cows.

Officials said Wednesday that they believe they have found a herd-mate to the infected Washington cow. DNA test results on the animal, one of 81 believed to have come into the USA from Canada with the infected cow, are expected early next week.