The failure to enforce regulations may be to blame for a U.S. case.

WASHINGTON – A Holstein dairy cow that contracted mad cow disease was older than originally believed, U.S. agriculture officials said Monday, a finding that may rebut suggestions that the government failed to enforce regulations to prevent the disease.

Inspectors also said that the age of the animal supports evidence that the cow was born in Canada, and probably was infected there.

Ron DeHaven, chief veterinary officer for the Department of Agriculture, said the owner of a Mabton, Wash., farm where the diseased cow was housed had found records indicating that the cow was 6 1/2 years old, instead of 4 as originally reported.

That finding cleared up the major discrepancy between U.S. and Canadian records about the diseased cow, and it bolstered U.S. confidence that the problem originated north of the border, a claim that Canadian officials have called premature.

Officials tracked the cow to the Canadian province of Alberta by a metal numbered ear tag but were initially perplexed because the animal’s age didn’t match Canadian records. They are now awaiting DNA testing to make a definitive determination whether the cow originated in Canada.

The cow’s age is also significant to the question of whether it slipped through U.S. regulations designed to prevent an outbreak.

The U.S. Food and Drug Administration and its Canadian counterpart imposed rules in August 1997 prohibiting the mixing of cow brain and spinal cords – which can spread the disease – into cattle feed. A congressional report last year criticized the FDA for lax enforcement of the rules.

If the diseased cow was born in April 1997, it could have eaten contaminated feed before the regulations were put into place. That would imply the animal simply predated the rules, not that the enforcement of the rules was inadequate, authorities said.

The cow was one of 74 from an Alberta dairy herd that were shipped to the U.S. in August 2001.

DeHaven said another eight cows from the same herd were shipped at a later date.

Investigators are tracking down the remaining 81 cows to determine if they are also infected with mad cow disease.

While trying to quell public fears of eating beef, U.S. officials are also trying to reassure export customers that they should lift their bans on buying American beef.

A delegation of USDA officials met Monday with Japanese authorities, who said it was too soon to resume buying U.S. beef. Japan is the biggest importer of American beef.

The diseased cow was brought to a Moses Lake, Wash., slaughterhouse on Dec. 9 because it had become disabled while delivering a calf.

The brain and spinal tissue from the cow were removed at the slaughterhouse and tissues were sent to the USDA’s lab in Ames, Iowa, while the rest of the cow was sent on to three more processing plants where it was turned into ground beef, beef patties and trimmings.

In the 17 years since an outbreak of mad cow disease in England, the U.S. has developed a system that tests the most vulnerable population of cows for the disease: those that exhibit signs of neurological problems or older cows that cannot walk. In the last two years, the USDA has tested about 20,000 cows a year out of the 35 million that are slaughtered annually.

While the number seems statistically insignificant, officials argue that by concentrating testing among the most vulnerable population, the USDA should be able to catch a one-in-a-million case of the disease.

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.