January 11, 2004 The Associated Press by MARK SHERMAN

"Calves don't care," says Jim Quigley, an executive with an Iowa company that produces a milk substitute given to the calves of dairy cows. Their milk is more valuable when sold for human consumption.

Researchers and consumer advocates increasingly are focusing on animal blood as a possible source of transmission of the range of brain-wasting diseases, including mad cow.

They contend the use of these protein supplements is a risky gap in the U.S. and Canadian bans on feeding most cattle proteins to other cattle. The bans, which went into place in 1997, are intended to prevent the spread of mad cow disease, which scientists believe is most likely transmitted through contaminated feed.

"This idea that blood can't transmit this disease is absurd," said John Stauber, co-author of "Mad Cow USA: Could the Nightmare Happen Here?"

The diagnosis last month of a case of the brain-wasting disease in a Washington state cow has brought renewed attention to the issue. U.S. and Canadian officials have pledged to take a renewed look at the use of cattle blood in products consumed by cattle.

"There has been no compelling scientific evidence that blood products pose a threat of transmitting the disease," said Sergio Tolusso, feed program coordinator for the Canadian Food Inspection Agency.

Still, Tolusso said, with the Washington state case and the discovery of the disease in a Canadian cow in May, "We have to rethink our position and perhaps make a change."

The Food and Drug Administration, which regulates animal feed in the United States, also is re-evaluating its policy. "We will be announcing further steps soon related to the feed ban," the agency's commissioner, Mark McClellan, said Friday.

Scientists have long said it is at least possible that blood can transmit the human version of mad cow disease.

In Britain, where mad cow first appeared in the 1980s and people began dying of the variant Creutzfeldt-Jakob disease in the mid-1990s, surgeons rely on imported blood during operations.

In the United States, people who spent significant time in the United Kingdom and Europe are not permitted to donate blood.

Last month, the British government announced that a man who died from the human form of mad cow disease might have gotten sick because of a blood transfusion. The man died six years after receiving blood from a donor who later developed the disease, the government said.

British researchers say they also have succeeded in passing along mad cow disease to animals through blood transfusions from infected animals.

Dr. Giuseppe Legname, a professor of neurology at the University of California at San Francisco, said there is no definitive answer about the infectious nature of blood. Legname works on the research team headed by Dr. Stanley Prusiner, the Nobel laureate who discovered the prion, or misshapen protein, that carries mad cow.

Prusiner has said it is "stupid" to feed cattle blood to cattle.

Legname said, "Before we can demonstrate one way or the other, it's safer not to use it."

The APC Co. of Ames, Iowa, continues to market its milk substitute derived from cattle blood and has no plans to change, said Jim Quigley, an APC vice president, and other executives. Quigley's comment about the color of the milk replacer appeared in a company-sponsored newsletter on raising young dairy calves.

In an interview, APC executives maintained there is no evidence suggesting their milk replacer is unsafe.

"We continue to get the indication that the blood is a safe tissue," said Louis Russell, a vice president. "We hope that there's no change. We don't think there's any reason to make a change."

Cattle blood is present in the cuts of beef that agriculture officials repeatedly have said are safe to eat, even in an infected cow, company executives said.

Such claims do not reassure Michael Hansen of Consumers Union. He pointed to Britain, which has had the largest outbreak of mad cow disease and where the feed ban includes blood.

Hansen said it should not matter to regulators that there are no studies documenting a case of the disease from the consumption of blood-based calf formula.

"The reason blood products are unsafe is that blood has been shown to transmit the disease," he said.