WASHINGTON — The U.S. Agriculture Department said Monday it was ending its search to find animals connected to the nation's first case of mad cow disease, though officials acknowledged they hadn't found all the animals they sought.
“Our investigation is now complete,” Ron De Haven, the department’s chief veterinarian, told reporters in a telephone conference call. “We feel very confident the remaining animals, the ones we have not been able to positively identify, represent little risk.”
Of greatest concern were 80 other head of cattle born on a farm in Alberta, Canada, and shipped into the United States in 2001, all part of the same herd that included the infected cow. Of the 81 cows sought, authorities were specifically trying to track down 25 considered most likely to have eaten the same potentially infectious feed given to the Washington state Holstein that tested positive for mad cow in December.
Including the single infected cow, officials found 29 of the 81 cows; of the 25 high-risk animals, officials tracked down 14. That leaves the whereabouts of 11 high-risk cows a mystery.
“We never expected to be able to find all of them,” DeHaven also said, noting that a paper trail no longer exists for some of them.
Other animals at one time carried ear identification tags but the tags may have been lost over the years, he said.
Certain methods of spreading the disease leave other questions about the probe. One practice thought largely responsible its spread in Europe was the use of cattle protein in animal feed.
Though that feed has not been legal for use on cattle in the United States and Canada since 1997, the U.S. government felt contaminated feed given to the herd in Canada might be responsible for the infection, hence the trace of the 25 cows. But because rendering plants batch large portions of animal protein, it is possible that feed containing the disease was more widely spread.
However, officials were able to track down 2,000 tons of rendered protein into which tissue from the infected Holstein could have been mixed, said Dr. Stephen Sundlof, director of the Food and Drug Administration’s Center for Veterinary Medicine, which regulates animal feed. That material is being destroyed, Sundlof said.
The large amount of tissue had to be quarantined because processors commonly mix byproducts from many cattle. “It was impossible to distinguish that which just came from the cow from all of the material that was out there,” Sundlof said.
The search for the 81 cattle in the so-called "index herd" led authorities to 189 farms and ranches and the testing of 255 "animals of interest," none of which had bovine spongiform encephalopathy or BSE, the technical name for mad cow, De Haven said.
Some may have gone to slaughter, though they would have been subject to the government's BSE surveillance program, which tested 20,000 cows last year and expects to test about 40,000 this year. About 35 million head of cattle are slaughtered each year in the United States. While that frequency of testing complies with international standards, it falls well below practices in some European countries and in Japan, where all beef is tested for BSE.
Also unknown is what happened to all 10,410 pounds of meat that was recalled from Vern's Moses Lake Meats, the Washington state slaughterhouse that processed the Holstein and mixed its meat with that of 19 other animals. Some may have been eaten, and one Seattle-area man has said he ate beef from the recalled lot.
As other officials have said repeatedly, DeHaven again insisted Monday the meat supply is safe. USDA had said the parts of the Holstein that could have contained infectious material, such as the brain and spinal cord, were removed before processing. And the recall was initiated out of “an abundance of caution,” he said.
Tough choices ahead
The USDA also faces challenges going forward as it implements a new system to test the U.S. herd for possible cases of mad cow disease. Despite the plan to test 40,000 cows this year, it has yet to determine how to choose cattle for testing. Prior to last December, when the first case of BSE was discovered, almost all cows tested were nonambulatory, known as "downers": cows that could not walk on their own and were usually being sent to slaughter because of their health issues.
The agency announced a Dec. 30 ban on all downer cows from the human food chain, part of a range of safety measures against BSE. With those cattle barred from consumption, officials must devise a new method to target cattle for testing.
At the same time, some former beef inspectors have voiced concerns about the government's testing and surveillance programs. And some who were present when the infected cow was slaughtered -- including the slaughterhouse worker who killed it -- have questioned whether the cow was a downer and was as sick as portrayed by federal officials.
Another setback for the USDA was dealt last week when an international review panel reported a “high probability” of more mad cow cases in the United States.
That panel, appointed by Agriculture Secretary Ann Veneman, said the U.S. government must impose far tougher safeguards to prevent mad cow disease in human food and animal feed. This included banning all farm animal remains from cattle food, and cattle brains and spinal material in animal feed and pet food.
The department was reviewing the panel’s recommendations, but had not yet come to a decision, DeHaven said.
Officials also reiterated their strong belief that the risk of humans contracting the disease, which can be transmitted by eating beef products that contain infected proteins, was minimal.
Push to resume exports
Part of the panel's role was to help establish safety determinations for U.S. trading partners, about 50 of which have banned U.S. beef, its byproducts or live cattle. Among them are Japan and Mexico, America’s best customers.
Though the panel's findings prompted some concern, the end of the probe announced Monday could be a valuable aid in the Bush administration’s efforts to persuade trading partners to resume purchases of American beef.
U.S. beef exports came to a virtual halt after the Dec. 23 announcement that a case of mad cow disease had been discovered in Washington state. The United States last year exported some $3.8 billion worth of beef products.
DeHaven said negotiations with Japan, Mexico and other trading partners would take on an “increased fervor” now that the investigation has ended.
USDA Undersecretary Bill Hawks last week traveled to Mexico -- the second-largest buyer of American beef -- to discuss meat trade issues. A USDA team will visit Japan, the biggest customer, in the next week or so.
MSNBC's Jon Bonné, The Associated Press and Reuters contributed to this report.