The carcass of a dairy cow slated to be rendered at a Fresno County, Calif. plant is infected with mad cow disease, federal and plant officials announced Tuesday.
The discovery of mad cow disease - only the fourth in U.S. history and the first in California - was made during routine testing of a dairy carcass headed to the Baker Commodities plant in Kerman.
Federal officials would only say that the carcass came from a "Central California" dairy, and local agricultural officials say they don't know whose cow it was. The central San Joaquin Valley is one of the largest dairy producing regions in the nation, with hundreds of dairies.
In announcing the find, federal and state officials were quick to reassure the public that the food supply is safe.
"Milk and beef remain safe to consume," said Karen Ross, California Department of Food and Agriculture secretary. "Because of the strength of the food protection system, the cow did not enter the food or feed supply."
Dennis Luckey, executive vice president of Baker Commodities, said that as part of the U.S. Department of Agriculture's surveillance system, carcasses that come through the company's dead-stock handling plant in Hanford are skinned and their brains randomly tested for bovine spongiform encephalopathy, or mad cow disease, before being rendered in Kerman. He said the plant generally services the central San Joaquin Valley.
The diseased carcass came into Baker's Hanford plant last Wednesday, was tested that day and samples sent to a University of California laboratory. The results came back inconclusive, but further testing at a USDA lab in Ames, Iowa, confirmed the cow was infected.
Luckey said 60 carcasses, including the cow with mad cow disease, were tested that day and all are being held at the Hanford plant while federal officials conduct their investigation.
USDA Chief Veterinary Officer John Clifford said Tuesday that the infected carcass will be destroyed, but Luckey said the company has not yet been told how it will dispose of the carcass or what will happen to the other carcasses.
In the San Joaquin Valley, dairy cows that have outlived their usefulness are routinely sent to rendering plants where they are processed into bone meal and tallow. The Kerman plant does not process any products for human consumption.
The USDA has not disclosed the dairy farm or farms where the infected cow spent its life. Doing so could impede the investigation, said Larry Hawkins, a spokesman in the Sacramento office of the USDA's Animal and Plant Health Inspection Service.
"At this point, we're not providing information that would lead somebody to go out and point the finger at a particular dairy," he said.
Tulare County Agricultural Commissioner Marilyn Kinoshita said she has not been told which dairy - or even which county - the infected cow came from.
But Tulare County Supervisor Pete Vander Poel said it would not surprise him if the animal was from Tulare County, given that Tulare is the No. 1 dairy county in the state.
Vander Poel said a USDA official told him by phone on Tuesday that the animal was from a five-county area of Central California, but did not identify the county.
Hawkins said investigators are trying to determine how the cow got the fatal disease. What is known, based on the tests, is that the cow did not get sick by eating a contaminated feeding source. The federal government banned the use of animal parts - a suspected source of mad cow disease - from cattle feed in 1997.
Christina Sigurdson, assistant professor of pathology at the University of California at San Diego, said atypical mad cow disease usually occurs in older cattle and the origin is not known.
Scientists speculate that atypical mad cow disease happens in cattle similar to sporadic Creutzfeldt-Jakob disease in people - a degenerative brain disorder thought to arise without any exposure to prions, or abnormal proteins.
Jim Sullins, University of California Cooperative Extension farm adviser for Tulare and Kings counties, said classical mad cow disease such as the kind found in England in the 1990s causes cattle to stagger and act erratically, he said.
By contrast, cattle affected with the atypical form show no outward signs of being affected, but their brain tissues shows deterioration, he said.
As agriculture investigators try to determine if any other cows are infected, agricultural officials and members of the beef and dairy industries were working hard Tuesday to try to reassure the public that the nation's food supply is safe and there is no risk to public health.
"Evidence shows that our systems and safeguards to prevent BSE are working, as are similar actions taken by countries around the world," said Clifford, the USDA veterinary chief. "In 2011, there were only 29 worldwide cases of BSE, a dramatic decline and 99 percent reduction since the peak in 1992 of 37,311 cases."
Tom Talbot, a California beef producer and chairman of the National Cattlemen's Beef Association Cattle Health Committee, echoed Clifford's message.
"Consumers should rest assured that U.S. beef is completely safe to consume and beef producers remain committed to producing safe, healthy beef for consumers," Talbot said. "Because this incident was detected prior to slaughter, consumers can be confident that the system set in place to prevent diseased animals from entering the food chain is working as it was designed to."
California's dairy leaders also reminded the public that drinking milk is also safe. Clifford, the USDA's chief veterinary officer, said BSE cannot be transmitted through milk.
And at least one expert said Tuesday's news may not have a huge effect on beef prices.
Mike Miller, senior vice president of global marketing and research at the National Cattlemen's Beef Association, does not expect a swift reaction from consumers, given that the cow was not intended for human consumption.
"I think this may cause a little bit of a pause among consumers," Miller said. "But we are nearly into the month of May and grilling season is upon us. Indications are that people will move full speed ahead."
(Fresno Bee staff writer Barbara Anderson and Modesto Bee staff writer John Holland contributed to this report.)