FORT WORTH -- Although meat from a 12-year-old Texas beef cow with mad cow disease never entered the food supply, critics of the US Department of Agriculture said the twisted, seven-month-long tale of this animal highlighted bureaucratic missteps and weaknesses in the food safety system.
Public confidence was not enhanced last month when the USDA announced that a private veterinarian had ''forgotten" about a brain tissue sample he took in April. It came from another cow that was suspected of having had the brain-wasting disease bovine spongiform encephalopathy, or BSE. On Wednesday, the USDA said that cow tested negative for the disease.
Watchdog groups awarded barely passing marks to the department for its handling of the case; the cow turned up dead at a Waco packing plant Nov. 15. The USDA finally confirmed the mad cow case June 10 after multiple tests.
''USDA gets a D or D minus," said Caroline Smith Dewaal of the Center for Science in the Public Interest, an advocacy group based in Washington. ''The best thing that came out of this is the work of the inspector general."
It was the department's in-house watchdog, Inspector General Phyllis Fong, who skirted the USDA hierarchy by ordering retesting with a different method more than six months after a routine second-round test, known as the immunohistochemistry, or IHC, test proved negative for the disease.
Agriculture Secretary Mike Johanns, who assumed office in January, has said he neither knew about nor authorized the retesting by the National Veterinary Services Laboratories in Ames, Iowa.
Just why Fong, a lawyer who grew up in Hawaii, acted in such a forthright, hierarchy-dodging manner has puzzled many involved in the industry.
In a statement, her office said the retesting was prompted by a review of ''voluminous records" showing an unusual pattern of conflicting test results in the case. Industry sources say there is speculation that she responded to concern expressed in scientific circles.
Two early tests, one reportedly conducted at Texas A&M University and a second in Ames, produced conflicting results -- one inconclusive, one negative.
What Fong and the public were unaware of was that Ames researchers had also used an experimental rapid version of the IHC test on brain tissue from the Texas cow. That proved positive for the disease, but staff members thought the result was technically flawed. The USDA did not disclose until just recently that the Ames lab had conducted the experimental test.
Months later, Fong stepped in and ordered more tests. A ''Western blot" test proved positive, as did later tests at a lab in Weybridge, England.
Finally in June, two days after the Weybridge lab confirmed the mad cow case, a chastened USDA announced that in addition to the routine IHC test, it was adopting the Western blot procedure whenever an initial ''BioRad" screening test indicates mad cow disease is possible. In addition, backup tests will now be conducted at Britain's national veterinary laboratory in Weybridge when earlier test results conflict or are inconclusive.
All this sounded familiar to Consumers Union.
In February, the nonprofit public interest group that publishes Consumer Reports urged the USDA to take those same steps in regard to the Texas cow, said Michael Hansen, a senior researcher with the organization.
Referring to the Texas cow, Dick wrote: ''We are confident in the expertise of USDA's laboratory technicians conducting BSE testing and do not feel that such confirmatory testing by the Weybridge laboratory is generally necessary, nor would the use of the Western blot test have enhanced the result of our November 2004 testing."
The opposite turned out to be true.
All the criticism might obscure the fact that meat from diseased livestock has been kept out of the food supply. Mad cow disease is carried by hard-to-destroy protein prions, which scientists believe can cause a rare human disease -- variant Creutzfeldt-Jakob -- if found in beef.
The food supply has been protected by a ban for human consumption of tissue most prone to prion contamination, including beef brain, scrapings from the spinal column, and a small section of the intestine.
Chief among the concerns of watchdog groups is that the United States -- unlike the European Union, Japan, Canada, Australia, and New Zealand -- has no mandatory national identification program for tracking cattle. An ID program could help trace the origins of a contaminated cow.
As the mad cow story developed this summer, the National Cattlemen's Beef Association said it was starting its own animal ID system.