29 From Herd Are Killed, Tested for Mad Cow

Investigators from the U.S. Department of Agriculture have slaughtered 29 animals from the Texas farm where a cow lived that tested positive for mad cow disease last month.

The 29 animals also were tested for mad cow disease as the USDA searches for any other animals in the herd that may have been infected.

Last month, brain samples from a 12-year-old Brahma cow tested positive for the brainwasting disease after the USDA inspector general ordered more tests on the animal. USDA lab officials initially had said the animal tested negative for the disease last November. Confirma- tion tests in England later proved the cow was infected.

No part of the animal ever entered the food chain.

The cow was first tested for bovine spongiform encephalopathy when it arrived dead at a pet-food plant in Waco, Texas.

The animal spent its entire life on a single Texas ranch. Officials have declined to provide more specific details about the ranch.

Animals in the herd that were in similar birth groups and possibly shared feed were removed from the herd for testing.

The animals were euthanized and tissue samples sent to the National Veterinary Services Lab in Ames, Iowa, for testing, said Jim Rogers, a spokesman for the USDA’s Animal and Plant Health Inspection Service.

The USDA uses a rapid test called BioRad to detect mad cow disease. Tissue yielding inconclusive results undergoes more detailed tests.

The USDA, in a posting on its Web site, did not say when test results would be available.

Rogers said it is unusual to find more than one case of mad cow disease in a cattle herd.

The USDA also stated that the agency is continuing to trace the infected cow’s last two calves, which it called “animals of interest.” Both animals are being traced through sale-barn records.

The epidemiological investigation continues as the USDA receives comments from the livestock industry about the need for a mandatory animal identification system. Meatpackers, pork producers and others are asking the USDA to increase efforts to initiate a mandatory tracking system by 2008. Cattle ranchers are seeking a volunteer system that would be in place by 2009.

The Texas animal represented the first case of mad-cow disease in an animal known to be born in the United States. The first U.S. case of mad cow disease found in December 2003 was traced to an animal born in Canada.