Gene Therapy Yields Bigger Pigs
by
Philip Brasher,
AP Farm Writer

1:35 AM EST; December 8, 1999; Washington, D.C. (AP) -- Someday, hogs may not have to eat like pigs. Scientists say they've found a way to genetically alter young hogs so they grow 40 percent faster and larger than normal swine -- on 25 percent less feed. The technology would be a boon for livestock farmers by lowering their costs, and it eventually could even be used to treat children with growth problems and to prevent muscle deterioration in AIDS or cancer patients, the researchers say. Their intervention stimulates the release of the animal's own pituitary growth hormone.

"We think this clearly is one of the new ways that agriculture will be improved in the next decade,'' said the lead scientist, Robert J. Schwartz, a Professor of Molecular and Cellular Biology at Baylor College of Medicine in Houston, TX. The researchers' findings are published in the current issue of Nature Biotechnology. "The technology could be used in humans as a less-expensive, more natural alternative to injecting AIDS patients with growth hormones, a treatment that costs as much as $20,000 a year," Schwartz said. A drug could be administered to switch patients' hormone secretions either on or off.

The prospect of high-tech hogs is likely to raise new questions in a growing worldwide debate over genetically engineered food. The United States already is locked in a trade war with the European Union over the EU's ban on beef from cattle injected with hormones. Livestock and poultry have been getting steadily bigger, leaner, and faster-growing for years because of improvements in genetics, nutrition, and housing, and the use of hormones in cattle, but the results reported by Schwartz's team are especially dramatic. All the improvements made in hog production over the past two decades have pigs maturing only 10 percent faster than they used to. The key to the new technology is a synthetic chemical that's inserted into a biodegradable piece of DNA and then injected into the leg of a 2-week-old pig. The chemical in turn causes the pig's pituitary gland to secrete higher than normal levels of growth hormone. Two months after the injection, treated pigs weighed 92 pounds, compared with 65 pounds for an untreated hog. The treated pigs eat 25 percent less feed, which would amount to a huge savings for the farmer, and they are even ready for slaughter two weeks earlier, Schwartz said in an interview Tuesday. The price of feed alone accounts for half the cost of raising a hog. "As a further benefit, the pigs are expected to produce less manure," he said. Remember that hog waste is a growing environmental concern in many states.

Further research will have to be done to show that the meat is safe for human consumption, and the treatment has no negative long-term impact on the animals. The treatment would have to be approved by the FDA before it could be used commercially. "This is extremely interesting work, but there may be some problems with how consumers will perceive it," said Max Rothschild of Iowa State University, one of the nation's leading authorities on pig genetics. "Will consumers eat animals that are treated in such a fashion? The jury is still out. ... In Europe, the answer is absolutely not," Rothschild said. It would be less controversial to continue improving pigs by identifying genes that control growth and other traits, he said.

Rebecca Goldburg, Senior Scientist for the Environmental Defense Fund, said in an interview Tuesday she's skeptical that the treated pigs would be as healthy as normal ones. "Animals as a whole are less plastic than plants. When their systems are disturbed by genetic engineering, their whole system can go out of whack," she said.

The study was financed by the Baylor College of Medicine, the Agriculture Department's Children's Nutrition Research Center, the National Space Biomedical Research Institute, as well as private sources.