When the government approves food from cloned animals, expected in the next year, the Food and Drug Administration doesn't plan special labels. Government scientists have found no difference between clones and conventional cows, pigs or goats.
However, shoppers won't be completely in the dark. To help them sort through meat and dairy products, one signal is the round, green USDA organic seal, says Caren Wilcox, who heads the Organic Trade Association.
While many people choose organic to avoid pesticides or antibiotics, Wilcox says the U.S. Department of Agriculture label also means clone-free.
"Organic animal products will not come from cloned animals," she said.
Cloning is taboo to Organic Valley, the country's biggest organic farming cooperative.
"This is absolutely prohibited in our world. It goes against everything we believe," said George Siemon, CEO of the 700-member cooperative. "Organic is based on having plenty with what nature's given us."
"Clone-free" labels are also likely on some nonorganic food, such as ice cream made by Ben & Jerry's Homemade Inc.
Still, it's unclear how much cloning will matter to consumers.
The nation's milk industry worries that people might reject food from clones or turn away from dairy products altogether. But so far, public opinion appears mixed. In a September poll by the Pew Initiative on Food and Biotechnology, 64 percent said they were uncomfortable with animal cloning.
In a December poll by the University of Maryland, the same percentage said they would buy, or consider buying, such food if the government said it was safe.
"The answers weren't yuck versus yes, not for the consumers that are provided information," said Barb Glenn, director of animal biotechnology for the Biotechnology Industry Organization.
People who can afford it will pay more for organic products, which are grown without toxic pesticides and fertilizers, antibiotics or synthetic growth hormones. Organic food is also grown without genetic engineering.
Organic is a rapidly growing segment of the nation's food market. Organic sales have grown by up to 20 percent annually; overall growth in food sales is around 3 percent.
Some in Congress want to require labels on food from clones. Sen. Barbara Mikulski, D-Md., has introduced legislation to require this note on packages: "This product is from a cloned animal or its progeny."
Mikulski and other critics disagree with FDA, which has said labels probably are unneeded because clones and their food are as safe as conventional versions.
"The FDA has gone astray, insisting that anytime they say a food is safe, consumers are obligated to eat it," said Carol Tucker Foreman of Consumer Federation of America.
The dairy industry says the bill would hurt their business.
"A huge burden would be on every single milk, cheese and ice cream company in this country, large and small, to provide 100 percent traceability and segregation and labeling of their milk," said Susan Ruland, spokeswoman for the International Dairy Foods Association.
"This is for a kind of milk that isn't even out there yet and that we're not even sure anyone is going to produce," Ruland said.
According to biotech companies, it may be difficult to promise that food is clone-free.
The purpose of cloning is not to put lots of cloned livestock into the food supply. The purpose is to make a genetic copy of a superior animal and put its offspring into the food supply.
Scientists have found no difference in clones or their offspring, and they have detected no difference in the animals' meat or milk. That could make it tough to keep offspring, and their progeny, out of production.
"You can't distinguish these animals from other animals," Glenn said. "It's almost mind-boggling, when you start talking about the granddaughters of granddaughters of granddaughters."
For organic, some question whether clones or their offspring really go against the rules.
The Agriculture Department was asked to address cloning when the organic standards were written, a process that drew comments from more than 300,000 people and organizations. The standards, which took effect in 2002, do not mention clones or their offspring; instead, they say genetic engineering is not allowed.
That is a source of disagreement between the department and the cloning industry.
Department officials say cloning is forbidden in organic animals. The process is incompatible with the standards, says Lloyd Day, head of the Agricultural Marketing Service, which governs the organic industry. The department still must decide whether the offspring of cloned animals are allowed, Day said.
Cloning companies disagree. They note the FDA says cloning is not genetic engineering. The idea of genetic engineering is to take away or add genes, while cloning leaves the gene sequence intact.
"Our interpretation is that cloning is not excluded at this time," Glenn said.
Rather, FDA says cloning is a technology that help animals reproduce, similar to in vitro fertilization and artificial insemination. And in vitro fertilization is allowed under organic production rules.
The government has asked producers to voluntarily keep clones away from the food supply until final approval is granted.