WASHINGTON — After exhuming the Alabama cow with mad cow disease, the government has concluded she was at least 10 years old and could have been infected before the government took steps to prevent the spread of the disease throught cattle feed, the Agriculture Department said.  

If the age had been much lower, that would have implied the prevention system broke down.

Nine years ago, the United States banned the use of ground-up cattle remains in cattle feed. Meat and bone meal from cattle was a common ingredient until infected material was implicated as the cause of a massive mad cow outbreak in the United Kingdom in the 1980s and 1990s. The disease was blamed for the deaths of 180,000 cattle and more than 150 people.

Experts checked the Alabama cow’s teeth and determined she was 10 or older, the department said Thursday evening.

Earlier, an official said the age is an approximation.

“After 5 years old, it is an approximation, but a fairly good approximation, in terms of looking at the amount of wear on the teeth, are there teeth missing, that kind of thing,” said Ron DeHaven, administrator of the Agriculture Department’s Animal and Plant Health Inspection Service.

Despite the ban on cattle remains in feed, potential pathways for infection remain. Among them is restaurant plate waste, including meat and bones, which can be added to cattle feed.

The cow spent less than a year on the Alabama farm, which has not been identified. Investigators are trying to find sale records and other documents to determine where the cow was born and raised and to find cows from her original herd.

They’re also looking for offspring and have located one of her calves. The six-week-old calf has been shipped to a department laboratory in Ames, Iowa, for observation, the department said Thursday.

Tissue samples from the cow will be used for DNA analysis to find siblings and offspring. Those efforts are precautionary; it is unusual to find mad cow disease in more than one animal in a herd or in the animal’s offspring, the department said.

The cow, a red crossbreed, was unable to walk — a “downer” cow — when the local vet examined her last week. The vet killed the cow and removed brain samples for testing, because downers are considered at risk of having mad cow disease.

Follow-up tests indicated the presence of mad cow disease.

The department is consulting other agencies to decide how to dispose of the carcass, according to DeHaven.

Mad cow disease is the common name for a deadly nerve disorder known as bovine spongiform encephalopathy, or BSE. Eating meat products contaminated with BSE is linked to variant Creutzfeldt-Jakob Disease, a rare but fatal nerve disease.

Two other cows have been diagnosed with mad cow disease in the U.S. The first case was confirmed in December 2003 in a Washington state cow that had been imported from Canada. The second was confirmed last June in a Texas-born cow.

In other developments:

n South Korea was reconsidering its resumption of limited imports of American beef because of the new case of mad cow in the United States.

The Agriculture and Forestry Ministry said it will stick to an earlier pact to resume imports by April of meat from young American cattle — widely believed to be safe from the disease — if the latest infected cow is found to be more than 8 years old.

That appeared likely, after the USDA said the cow was 10 years old.

But Kim Chang-seob, chief veterinary officer at the Ministry of Agriculture and Forestry, said the infected cow's age had yet to be scientifically confirmed. He did not say what further proof South Korean officials would require.

n Officials in Japan have confirmed the country's first case of mad cow disease in cattle raised to provide meat, an official of the Health Ministry said. 

   A 14-year-old cow in the southern prefecture of Nagasaki was confirmed to have been infected with the disease, said the official, who declined to be named citing ministry policy.

 Japan previously confirmed 23 cases of the disease, but they all involved cattle bred to produce milk.

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On the Net:

Agriculture Department: http://www.usda.gov

Alabama agriculture department: http://www.agi.state.al.us/