Nov. 25, 2003 Early in November, the Food and Drug Administration released preliminary findings that meat and milk from cloned animals could be consumed safely by humans. Does that mean cloned turkeys will eventually make their way to your Thanksgiving table? A University of Arkansas expert says no.
"No one has succeeded in cloning a chicken or turkey to my knowledge," said John Kirby, a professor of poultry science. "The structure of the egg makes cloning a far more complicated process in birds than in mammals. On top of that, it would be prohibitively expensive to produce cloned birds for mass consumption."
According to Kirby, the FDA report referred to livestock cloned from embryonic cells, a process that closely resembles the formation of identical twins. For example, an embryo may be removed from the oviduct of a cow and the cells within that embryo separated and independently cultured. Because each blastodermic cell in an embryo is capable of dividing and multiplying, the process results in multiple developing embryos where previously there had been only one. These embryos are implanted in the cow, thereby producing several genetically identical calves. The structure of birds’ eggs makes this cloning process much more difficult for turkeys and chickens, Kirby said.
That doesn’t mean our fine-feathered friends have been wholly excluded from genetic tinkerings, however. Though they can’t yet clone a chicken or turkey, researchers have produced transgenic birds, with DNA from other organisms spliced into their genetic code. It’s a process that largely has been reserved for medical research, Kirby said. Scientists can introduce genes that instruct the bird to produce specific proteins – for example, specific human antibodies. These antibodies can then be extracted from the albumin of the transgenic bird’s eggs and used to passively immunize humans against specific molecules or organisms.
In the past, scientists have used the bacteria E.coli or yeast to produce human antibodies in this manner. But because chickens and turkeys are more complex organisms, the proteins they produce are more highly structured, Kirby said. Their systems not only copy the sequence of amino acids that comprise the protein, they also add essential modifications and fold the protein to ensure proper functioning in humans. In addition, turkeys and chickens can produce greater quantities of the protein – up to a gram each day.
The FDA has yet to announce a policy on transgenic animals, but Kirby asserts that these modified birds will not enter the human food chain.
"Part of the reason you’ll likely never eat a transgenic chicken is that they’re so valuable to medical research. There are very specific handling protocols for transgenic animals. They’re tracked from birth to death, and then their bodies are incinerated," he explained. "Besides that, they’re usually leghorn chickens," too tough and scrawny to eat.
Though much speculation and some protest have arisen about genetically modified and cloned products entering the food chain, Kirby claims there’s no real need to be concerned about chicken or turkey. Poultry geneticists have found great success in producing bigger, tastier birds simply through selective breeding. Currently, there’s no need to explore costly, controversial breeding and production techniques.
"We’ll be eating good old fashioned turkey for decades to come," he said. "I don’t foresee anything different happening in the near future."
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