"We clone an animal because we want a genetic twin of that animal," said Barb Glenn of the Biotechnology Industry Organization.

"It's not a genetically engineered animal; no genes have been changed or moved or deleted," she said. "It's simply a genetic twin that we can then use for future matings to improve the overall health and well-being of the herd."

Thus, consumers would mostly get food from their offspring and not the clones themselves, Glenn said.

Still, some clones would end up in the food supply. As with conventional livestock, a cloned bull or cow that outlived its usefulness would probably wind up at a hamburger plant, and a cloned dairy cow would be milked during her breeding years.

That's unlikely to happen soon, because FDA officials have asked farmers and cloning companies since 2001 to voluntarily keep clones and their offspring out of the food supply.

The informal ban would remain in place for several months while FDA accepts comments from the public.

Approval of cloned livestock has taken five years because of pressure from big food companies nervous that consumers might reject milk and meat from cloned animals.

To clone, scientists replace all the genetic material in an egg with a mature cell containing the complete genetic code from the donor. Cloners argue that the resulting animal is simply the donor's twin, containing an identical makeup. Yet there can be differences between the two because of chance and environmental influences.

Some surveys have shown people to be uncomfortable with food from cloned animals; 64 percent said they were uncomfortable in a September poll by the Pew Initiative on Food and Biotechnology, a nonpartisan research group.

A dairy industry spokeswoman said last week it would be reassuring if the FDA concluded there were no safety issues.

"It remains to be seen whether dairy farmers will even choose to use it," said Susan Ruland, spokeswoman for the International Dairy Foods Association, which represents such brands as Kraft and Dannon.

"There are very few cloned dairy cows in this country ¡ª only about 150 out of the 9 million total US dairy cows, and many of these are show animals," Ruland said.

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