Ending seven months of uncertainty, the U.S. Agriculture Department confirmed that a cow first suspected of having Mad Cow Disease in November had tested positive -- the second such case identified in the United States.

Agriculture secretary Mike Johanns, calling U.S. beef "the safest in the world," said the case of Bovine Spongiform Encephalopathy (BSE) posed no threat to public health because the animal was not sent to a food processing plant.

"The BSE threat to humans in this country is so remote that there is a better chance you'll get hurt crossing the street to get to the grocery store than by the beef you buy in the grocery store," he said.

Johanns praised the USDA's testing regimen for BSE, saying positive tests were so rare it would be like "finding a needle in a haystack."

He also announced that department scientists had been ordered to develop a new protocol for dealing with cases in which initial tests for Mad Cow Disease were inconclusive. Also, he said USDA would reexamine the system for storing the remains of suspect animals.

The latest case of Mad Cow Disease, however, raised concerns in the cattle industry that consumers would turn to poultry and pork and that trading partners would continue to ban U.S. beef from their markets.

Consumers largely shrugged off the previous U.S. incident, the December 2003 discovery of a Washington state dairy cow infected with BSE.

That cow was imported from Canada, which earlier had a BSE discovery, and was born before a 1997 Food and Drug Administration rule prohibiting the feeding of ruminant meat and bone meal to cattle. The use of remains from cows, sheep and other ruminants as feed is suspected to be one of the key ways the disease is spread.

USDA officials refused to identify where the second infected animal was when it was slaughtered in November. They said they were investigating the cow's herd mates to determine how it got the disease. The animal reportedly was a Texas beef cow, born before the ban, that was slaughtered for pet food.

Food safety experts said there still was little chance of consumers eating contaminated meat, which is linked to a human form of BSE known as variant Creutzfeldt-Jakob disease. The disease in humans has no treatment and is always fatal. It has affected 153 people worldwide, most of them in Britain. That country has found more than 180,000 animals infected with BSE.

By comparison, this was the second case found among an estimated 100 million head of cattle in this country.

"Happily, the risk of contracting the human form of Mad Cow Disease is minuscule," said Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest, a Washington advocacy group.

However, DeWaal criticized the nation's lack of a mandatory animal tracking system.

"This cow was exposed at a time early in its life," she said. "Because we don't have a tracking program, we don't know where it was born, where it grew up and what other animals might have been exposed."

DeWaal said the USDA had delayed implementation of such a system until 2009, though Canada was able to move from a voluntary to a mandatory animal tracking system in one year.

Critics said, in the case of the second infected animal, it was only after prodding by the department's inspector general that officials took the action that led to this announcement.

On November 18, the USDA announced that two preliminary Mad Cow tests on an animal were inconclusive. More sophisticated tests were ordered, and on November 23, officials announced that the new tests were negative. Officials said they were confident the animal was free of Mad Cow Disease.

In February, the Consumers Union advocacy group urged the USDA to use a more sophisticated method called the "Western blot" test. This month, the USDA's inspector general also recommended using the Western blot test, which resulted in the announcement that the animal had Mad Cow Disease.

Some ranchers and animal rights groups accused the administration of foot-dragging on key reforms promised after the first cow tested positive in December 2003.

They said the government had not yet imposed a permanent ban on allowing nonambulatory animals, called downers, into the food supply. Nor had they taken steps to ensure that cattle feed was free of animal parts.

"This administration's response to Mad Cow Disease appears to be more public relations than public health," said Rep. Henry A. Waxman (D-Los Angeles), who called for a congressional investigation into "what went wrong."

Officials proposed a ban on downer cattle after the first Mad Cow case in the U.S. was discovered, and the USDA received 22,000 comments, mostly positive. However, department officials made no move to finalize the ban and recently talked about easing the rules on downer cattle.

Bill Bullard, the chief executive of R-CALF, a national association of ranchers and cattle producers, agreed that the downers should be banned from slaughter. He said the FDA, which already had banned feeding animal parts to cows, should also block two other possible sources of contamination: animal blood and poultry litter and waste.

"We think USDA needs to be strengthening its testing so they can accurately monitor the evolution of the disease," Bullard said.

Under the system, downers are slaughtered but not moved into the food supply; of the estimated 600,000 downer cows slaughtered in the last 18 months, 388,000 have been tested.

Critics in Congress were outraged that the department had not ordered the second round of tests seven months ago.

"While the beef industry and the ranchers back in Washington state have been working nonstop to restore consumer confidence, the administration has been dragging its heels on important safety measures," Sen. Maria Cantwell (D-Wash.) said.

"How many Mad Cow cases must be discovered before the administration provides more than lip service?" she asked.

Johanns said the latest discovery would not interfere with U.S. plans to reopen the export market from Canada or with talks with Japan on resuming U.S. imports.

When the first cow was identified 18 months ago, the industry took a nearly $4 billion hit, as 53 countries banned imports of U.S. beef.

Americans spent about $71 billion on beef last year, eating more than 66 pounds per capita in 2004. That number was expected to be higher this year, according to Cattle-Fax, a beef research firm in Denver.

Despite the previous BSE finding, the record level of consumer spending on beef made 2004 an extremely profitable year for beef cattle producers, said Ben Higgins, spokesman for the California Cattlemen's Assn.