January 05, 2004

 

Mad Cow Investigators Focus on Common Feed Source

 

U.S. agriculture officials said Friday a third dairy herd in Washington state is under hold orders as authorities investigate the country's lone case of mad-cow disease.

 

So far, about a dozen of the 82 cattle that entered the U.S. with the infected animal on Sept. 4, 2001, have been located.

 

"The whereabouts of the other 70 have yet to be confirmed, but we have good leads on them," Dr. Ron DeHaven, chief USDA veterinarian, said during a media briefing Friday.

 

The mother, or dam, of the infected animal may be among those still being tracked down, he said.

 

DeHaven said the latest animal to be located was found on a dairy farm in Matawa, Wash. That facility was put under a "hold order" that prohibits removal of any animals from it pending further investigation.

 

Previously two herds in Washington, including that of the infected cow, came under similar orders.

 

As yet no animals under the hold orders have been killed, pending further investigation into how the infected dairy cow contracted the brain-wasting disease.

 

Among other things, authorities are awaiting DNA tests that would confirm the lineage of the infected cow and others from the same parents. DNA results from the infected cow are expected next week, DeHaven said.

 

Authorities in the U.S. and Canada now believe that the diseased cow was sired by semen from a bull in Canada. Semen from the bull is part of the DNA testing.

 

Mad-cow disease, or bovine spongiform encephalopathy, is believed contracted by eating feed containing bones or other material from contaminated cattle. But DeHaven discounted reports that the source of suspected contaminated feed in the current case had been located.

 

As for a possible link between the U.S. mad-cow case and one in Canada last May, DeHaven said, "It' s way too premature to draw any conclusions about whether there is a single feed plant, or even if there would have been similar sources of feed."

 

 

Investigators want to locate all animals that came into the U.S. from Canada with the infected animal "because it's possible they shared a common feed source when young and potentially had common exposure" to BSE, said DeHaven, chief USDA veterinarian.

 

Earlier this week, Agriculture Secretary Ann Veneman proposed a national identification system which, if in place now, presumably would make the tracing of the herd in question easier to accomplish.

 

Veneman also issued orders banning all nonambulatory, or "downer," cows from going to slaughter and entering the human food supply.

 

DeHaven said authorities are working on how to collect samples of downed, dead or diseased cattle on farms to determine whether they were infected with BSE.

 

Animals that leave farms seemingly healthy but break a leg or otherwise become nonambulatory upon reaching a slaughtering facility will be examined there by a veterinarian. If condemned, those animals also will be tested, and their carcasses disposed of after results are received.

 

Asked whether the government might offer financial incentives to cattle producers to test animals for BSE, DeHaven said "right now all options are on the table."

 

Various industry sources have put the cost of a single test at between $30 and $50.