U.S. agriculture officials so far are standing by their detection system for mad cow disease (search), despite complaints from consumer groups that testing is inadequate.

Monday was the first regular business day since the Agriculture Department (search) last week announced the nation's first case of mad cow disease in a Washington state dairy cow. Dr. Kenneth Petersen of USDA's Food Safety and Inspection Service (search) said no additional inspections had been ordered and meat from cows that were too sick or injured to stand or walk unassisted would continue to be allowed to be sold for human consumption, provided there was no evidence of neurological problems.

However, Petersen said, "The department is looking at what additional testing we need to do." Under consideration are increased testing and expansion of a ban on animal feed, officials said.

U.S. agriculture officials in Tokyo trying to persuade the Japanese to lift that country's ban on American beef said the United States soon would announce more stringent safety measures, a Japanese official said on condition of anonymity. The U.S. officials went to South Korea after their stop in Japan.

The diseased cow's meat was allowed to be sold for human consumption because a USDA inspector saw only signs of a physical injury to the cow.

USDA ordered a recall of more than 10,000 pounds of meat from 20 cows slaughtered on the same day at the same Washington state company. The recalled meat was distributed to eight states and Guam, although officials said 80 percent of it went to Oregon and Washington.

USDA officials have said they ordered the recall as a precaution, insisting there was no threat to the safety of the U.S. food supply.

Matt Baun, a USDA spokesman, said about 100 callers, mostly from Oregon and Washington, had called to say they had consumed recalled meat and were worried.

Baun said they were being told the meat was safe since it was muscle meat and not affected.

Consumers Union said the government was being too optimistic about the situation. "This incident only serves to underscore the urgent need for the U.S. to immediately undertake a massive mad-cow disease-testing program on beef," the group said in a statement.

Democrats were carefully watching how the Bush administration handles what could turn into a crisis for consumers and the beef industry.

The United States and Canada have banned brain and spinal cord tissue from use in cattle feed. Those tissues are the primary means by which the mad cow diseased is transmitted. The ban, which took effect in August 1997, prohibits feeding cattle to other cattle, sheep and goats.

The prion that causes mad cow disease is not found in muscle tissue, the source of roasts, steaks and other beef cuts. Dr. Ron DeHaven, USDA's chief veterinary officer, said studies have shown the prion is found only in the central nervous system tissue, the brain and spinal cord.

He said the bans on American beef products in more than 30 countries in response to the current case — the first known incidence of mad cow in the United States — have been based on perceptions of the disease and not on scientific facts.

Still, Japan said the United States should first establish the facts surrounding the infection before asking the ban be lifted, the Japanese official said.

Similarly, Canadian officials said their U.S. counterparts were too quick to say that the sick Holstein came from Canada, since genetic testing is not complete and the tainted feed that is the most likely source of infection could have come from either country.

Alberta Premier Ralph Klein said USDA's announcement angered him because the North American beef market was too integrated for that distinction to matter.

Authorities are looking for links between the Holstein infected with mad cow disease and a Canadian cow that was diagnosed with the deadly illness in May.

They also said they are searching for 81 Canadian-born cows from the same herd as the sick Holstein that records indicate entered the United States in late 2001.

Records confirm that the animal was born in Alberta, Canada in April 1997, DeHaven said. Alberta also was the home of the infected Canadian cow.

More significantly, both cows were born before the feed ban took effect.

The Food and Drug Administration has said that only 75 percent of animal feed producers were complying with the cattle-parts feed ban when it first went into effect, but that compliance has improved to close to 100 percent.