Supplements used in factory farming can spread disease
The Washington Post
The coldly regimented process of raising a dairy cow in North America forces it at an early age to depend on dietary supplements that in rare instances can spread mad-cow disease, according to livestock experts.
In addition, the frequent shuffling of young dairy cows between specialized feedlots and milking farms can make it difficult to track an infected animal to the herd where it was born, these experts say.
When these cattle move — even between Canada and the United States — they are not necessarily individually identified, said Mary Beth Lang, a spokeswoman for the Washington State Department of Agriculture. "There are ear tags," she said. "But they can fall off."
On large dairy farms in the United States and Canada, calves often are separated from their mothers within 24 hours of birth. The reason is money: The milk a dairy cow produces is worth far more on a supermarket shelf than in the stomach of her newborn.
So calves, male and female, are shunted away from many large dairy farms — usually within two weeks of birth — to specialized feedlots, where they are quickly weaned from milk and fed protein supplement pellets, along with hay. These calves depend on supplements for most of their protein intake until they are about 3 months old, when they are mature enough to digest cellulose and absorb protein on their own.
Bovine spongiform encephalopathy, or BSE, the brain malady known as mad-cow disease, can infect cattle that eat protein supplements made from the remains of cattle and other ruminant livestock. The disease is not transmitted by milk, which calves would normally be getting from their mothers.
"Because of the supplement regime, dairy cattle are especially susceptible to this problem," said Arthur Linton, a cattle geneticist and director of Washington State University's Irrigated Agriculture Research and Extension Center.
In the United States and Canada, the ground-up remains of cattle and other ruminants, or animals that chew a cud, were banned as ingredients for cattle supplements in 1997. But the General Accounting Office, the investigative arm of Congress, has twice criticized U.S. enforcement of the ban as lax.
The U.S. Department of Agriculture (USDA) announced yesterday that the Washington state dairy cow that tested positive this month for mad-cow disease probably came to the United States from the Canadian province of Alberta in August 2001.
The age of the infected animal remains in dispute. Canadian records show it was born in 1997, officials said, whereas U.S. records suggest it was about two years younger.
U.S. and Canadian investigators are trying to verify the birth herd of the infected Holstein and 73 other dairy cows that entered this country the same day.
Dairy calves are not uniquely susceptible to the risk of mad-cow disease. The only other North American cow that has tested positive for the disease was a beef cow. Beef cattle, though they usually stay with their mothers and suckle until they are at least 8 months old, are also fed some protein supplements.
But it is only in recent years, as many modern dairy farms have begun shuffling calves away from their mothers as soon as they are born, that dairy cows have become highly dependent on protein supplements for normal development.
On factory farms, female calves, called heifers, are far more valuable — and usually much more carefully fed — than bull calves. Bull calves from dairy herds are usually castrated, becoming steers, and sent to feedlots, where they are fattened for slaughter, usually before the age of 2.
A bull calf is typically worth about $100, but a heifer of the same age and breed is usually worth at least three times more. When such a cow reaches 27 months and is pregnant for the first time, she is worth nearly $2,000.
To protect their investment in these animals, many large-scale dairy farmers ship heifers to feedlots called "heifer development operations." There, they are put in individual pens and weaned from milk as quickly as possible.
Away from their mothers and quickly weaned, the heifers cannot develop normally without protein supplements. It takes 60 to 90 days for them to develop the four-chamber ruminant stomach that allows them to eat roughage and extract protein from it.
It is during this period that heifers are especially susceptible to infection from mad-cow disease, if they are eating contaminated protein supplements.
The Food and Drug Administration says that although enforcement of the ban on cattle remains in these supplements was flawed for a few years, compliance has reached 99 percent.
The USDA said last week it is moving to correct another byproduct of the modern cattle industry: lack of individual animal identification as cattle are rotated among various farms and feedlots and across state and international borders.
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