The U.S. Agriculture Department on Friday quarantined a second herd of cattle in Washington state in connection with the first U.S. case of mad cow disease, as cattle producers scrambled to minimize damage to the $27 billion industry.
The cattle industry, reeling from the discovery of the deadly, brain-wasting disease, on Friday withdrew objections to tighter controls that would prevent sick animals from entering the food supply.
White House officials said that the U.S. beef supply is safe for consumers and a spokesman said President Bush continues to eat beef.
The second Washington state herd placed under quarantine brings to 4,400 the number of animals under observation.
With more than two dozen countries banning the import of U.S. beef, including $1 billion-a-year customer Japan, federal Agriculture Department officials said their probe into the origin of the disease could take months and widen far beyond the dairy farm in Mabton, Washington, where the 4-year-old Holstein was discovered.
In Chicago, cattle futures fell by the maximum allowable amount for the second consecutive day and experts said beef prices could tumble by a further 20 percent and predicted that exports to Japan and other key market would be disrupted well into the new year.
Venezuela and Egypt on Friday joined some two dozen nations that halted imports of U.S. beef. Food company stocks also tumbled as investors worried that U.S. consumers could begin to eat less beef.
The U.S. Agriculture Department on Friday quarantined a second herd of 400 bull calves in Sunnyside, Washington, not far from Mabton, that contains a calf recently born to the original infected Holstein.
The USDA had previously quarantined a 4,000-animal herd at the dairy farm in Mabton, where the infected cow lived before it was slaughtered on Dec. 9. The cow was sent to slaughter after complications from calving left her unable to walk.
The U.S. Cattlemen's Association, the industry's major group, on Friday changed it position on dealing with sick cattle, saying that those are too sick to walk -- so-called downer animals -- should be tested for mad cow disease before they are slaughtered and processed for consumption.
The animal that came down with the nation's first case of mad cow disease had been made into hamburger and probably eaten before the U.S. Agriculture Department received test results.
Ranchers and farmers now support a "test and hold" program that segregated the carcasses of sick animals from others until testing for mad cow, Terry Stokes, chief executive officer of the National Cattlemen's Beef Association, said.
The cattle industry previously contended that downer cattle pose no clear-cut risk to the human food supply. A USDA spokeswoman said the department was reviewing all of its existing mad cow safeguards for possible improvements, but declined further comment.
The Food and Drug Administration (FDA) also said it was assessing its rules, with an eye toward possibly banning the use of cattle remains in all animal food.
The U.S. government said it was sending trade experts to Japan, the biggest single buyer of U.S. beef, to begin talks on Monday on how to address that nation's concerns and resume beef shipments.
An outbreak of mad cow disease, known formally as bovine spongiform encephalopathy (BSE), forced the slaughter of millions of cattle in Europe in the 1990s. At least 137 people, mostly in Britain, died of a human form of the disease, known as variant Creutzfeldt-Jakob disease.
In both cattle and humans, the disease destroys portions of the brain, causing paralysis and blindness. There is no cure.
The investigation to pinpoint how the U.S. cow was infected will take time, said Ron DeHaven, USDA's chief veterinarian.
"It might not be a matter of days, it might be a matter of weeks or months," DeHaven told reporters.
It was "highly unlikely" that BSE -- which is conveyed through infected brains, spinal column and nervous system tissue -- could be spread to other animals through birth, but scientists cannot rule out that possibility, he said.
The investigation by the USDA and the FDA focused on where the infected cow was born and what kind of feed she consumed early in life.
"We assume it was infected very early in life because the average incubation period is generally four or five years," said Stephen Sundlof, the FDA's chief veterinarian.
In 1997, the FDA banned the use of cattle remains as an ingredient in feed for other cows. However, cattle brains, spinal cords and other potentially risky material can be ground up and used in feed for poultry, pigs and household pets.
DeHaven also said it was "premature" to speculate whether the infected cow was born in Canada. In May, Canadian officials found a single case of BSE in a Black Angus cow in Alberta. Investigators were never able to determine the cause.
The U.S. probe could be broadened to "potentially many states," DeHaven said.
Shares in beef processor Tyson Foods Inc. were pounded again on Friday. Major hamburger chains like McDonald's Corp. recovered modestly, as investors tried to gauge the impact on consumer demand.
Credit rating agency Standard & Poor's on Wednesday placed the debt ratings of most U.S. beef protein processors on watch, with negative implications.