What's the beef?

In the beginning, there was Dolly. Since then, one by one, beef and dairy cattle, pigs, and goats have joined the Scottish sheep in a 21st century ark of cloned farm animals.

But while cloned animals have become common in the lab, they have yet to make it to the dinner table. That could change if the Food and Drug Administration overturns a ban on the consumption of cloned livestock. In a few years, their meat or milk could become a regular staple on America's menu.

The results could be significant: higher-quality meat and dairy products, foods engineered to be more nutritious, and possibly lower grocery prices, thanks to the arrival of more productive animals. The infant farm cloning industry is chomping at the bit to commercialize its research.

But consumer and animal advocates worry about the impact that cloning could have on human health, not to mention the animals themselves. There is no evidence "that food from cloned animals is safe," said Carol Tucker Foreman of the Consumer Federation of America in a statement. "The FDA has only limited data on the composition of food from cloned animals, and there have been no feeding studies to see the impact of long-term consumption. All of the data come from groups who support animal cloning."

So far, the signs for the industry look positive. Last October, the FDA said that food products from cloned livestock were essentially the same as those from conventional animals. It is working on a risk-assessment plan that, for now, indicates there is little risk to humans who eat cloned livestock. The release of the final assessment has yet to be scheduled.

Only a few hundred cloned cattle currently live in the United States, mostly on research farms, so a repeal of the ban would have little immediate effect on the food supply. However, dropping the barrier would dismantle a hurdle that has kept the industry in the starting blocks, proponents say.

"There's no question that the voluntary ban ... is holding the development of this business back," says Don Coover, a rancher from Galesburg, Kan., and owner of SEK Genetics, a cattle-genetics company with cloning partnerships. He has financed several cloning projects, including six clones of the high-performance bull, Full Flush. Full Flush's calves are healthy 2-year-olds and have increased in value more than five times their original production cost of $20,000, he says.

Cloned cattle like them could be used to breed uniform, high-quality offspring. "You could make animals with less fatty meat or more nutritious milk," says Lisa Dry, communications director of the Biotechnology Industry Organization in Washington. "Or they could be more resistant to diseases, which could make them safer for humans to eat."

Mr. Coover, who sells bull semen for artificial insemination, says there is a growing demand for that product from top-quality bulls. "There's quite a lot of interest in buying semen from the clones, but we're telling people that we're not going to do that," he says. "It's the obligation of the FDA to make a decision that is in the best interest of ... the producers and the broader public."

The FDA's preliminary decision, which is part of the formal risk-assessment process and thus not final, is based on findings from a National Academy of Sciences (NAS) report. Although the NAS study, commissioned by the FDA, said food from cloned animals was probably safe, it did express reservations.

"Limited sample size, health and production data, and rapidly changing cloning protocols make it difficult to draw conclusions regarding the safety of milk, meat, or other products from ... cloned [animals]," the NAS reported in August 2002.

But with cloning technology clipping along at a thoroughbred's pace, the FDA decided last fall to release 11 pages of its risk assessment, which considers cows, sheep, pigs, and goats. "Food products derived from animal clones and their offspring are likely to be as safe to eat as food from their non-clone counterparts, based on all the evidence available," FDA officials reported in October. "These scientific findings also showed that healthy adult clones are virtually indistinguishable from their conventional counterparts."

However, the FDA has acknowledged that it will explore animal-welfare issues. Research has shown that the cloning process severely affects the genetic makeup of animals and can cause clones to suffer. The Humane Society of the United States, for one, is deeply concerned about the ethical implications of cloning.

"Deaths and deformities in cloned animals are the norm, not the exception, and these studies make plain once again that these creatures are suffering terribly in the process," says Wayne Pacelle, senior vice president of HSUS. "There is no societal value to this. This is just science run amok in the service of the further industrialization of agriculture."

The main method of cloning involves taking the nucleus from a cell of the animal to be cloned and placing it in an egg that has had its nucleus removed. A University of Missouri study on cloned pigs, according to HSUS, reported that "out of 10 born, 5 died or were destroyed by researchers due to defects such as heart failure, lameness, and anemia."

Jorge Piedrahita and researchers at North Carolina State University's College of Veterinary Medicine announced last month that they had cloned two Duroc pigs. "Certain genes were dis-regulated or damaged," Mr. Piedrahita reported.

And in 2002 Rudolf Jaenisch, a researcher at MIT, reported that cloned mice have hundreds of abnormal genes. Some have a genetic tendency toward obesity.

The NAS has pointed out that ill clones would probably be more stressed as they reach maturity, and it suggested the animals might shed more pathogens in their manure. That would increase the potential of contaminated carcasses entering processing plants and, later, the food supply.

"While some forms of animal cloning may have inherent benefits, others are hard to justify," said the Consumer Federation's Ms. Foreman in a statement. "The FDA needs to make, or ask another government agency to make, some decisions about appropriate uses of cloning."