By Randy Fabi and Richard Cowan
WASHINGTON (Reuters) - An investigation into the nation's first case of mad cow disease could take months, the U.S. Agriculture Department said on Friday, after it quarantined a second cattle herd in Washington state.
The discovery of the deadly, brain-wasting disease in a four-year-old Holstein dairy cow in rural Washington state has cut off U.S. exports of beef, sent food company stocks tumbling and shaken consumer confidence.
The USDA said it would dispatch a team of trade experts to Japan, the biggest single buyer of U.S. beef, to begin talks on how to address that nation's concerns and resume shipments. Last year, Japan bought about $1 billion worth of American beef, veal and variety meats.
More than two dozen nations that buy U.S. beef have halted shipments, including announcements of a ban by Venezuela and Egypt on Friday.
The USDA's investigation to determine how the Holstein cow became infected will take time, said Ron DeHaven, the USDA's chief veterinarian.
"It might not be a matter of days, it might be a matter of weeks or months," DeHaven told reporters.
The USDA quarantined a second herd of young animals in Sunnyside, Washington, that contains a young bull calf recently born to the infected Holstein, he said.
Earlier in the week, the USDA quarantined a herd of 4,000 animals at another farm in Mabton, Washington, where the infected cow lived before it was slaughtered on Dec. 9. The cow was sent to slaughter after complications from pregnancy and calving, the USDA said.
She gave birth to two other calves during her lifetime, DeHaven said. DeHaven said it was "highly unlikely" that mad cow disease could be spread through birth but scientists could not rule out that possibility.
DeHaven also said it was "premature" to speculate whether the infected cow may have originated in Canada. In May, Canadian officials reported the discovery of a single case of mad cow disease in a Black Angus cow in Alberta.
The investigation by the USDA and the Food and Drug Administration could be broadened to other states, he said. "Potentially many states could be involved" in the probe, DeHaven said.
Cattle futures traded in Chicago opened down the 3-cent per pound daily limit on Friday. Live cattle futures for February delivery were at 86.175 cents per pound. Futures contracts for corn, a key animal feed, were higher across the board.
An FDA official said the investigation was focusing on the source of the livestock feed consumed by the Holstein cow.
"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.
Sundlof said all firms in Washington state that manufacture livestock feed are currently in compliance with FDA regulations. Since 1997, the agency has banned the use of cattle remains as an ingredient in feed for other cows.