Chinese scientists genetically engineered a low-fat pig. But for whose benefit?

In days since the paper was published, media outlets from New York to London have trumpeted the news that Chinese scientists have genetically engineered a pig that can better regulate its body temperature by burning fat in cold months. The side benefit? The hog ends up with leaner meat.

The genetic breakthrough has been heralded as something of a win-win for farmers and consumers: The former could lower the costs of raising their pigs, and the latter could get their pork fix without as many calories from fat. All of this, of course, assumes that a genetically engineered pig from China could be approved for human consumption in the United States, no easy feat considering that it took the Food and Drug Administration nearly two decades to give the green light to GE Atlantic salmon.

The fast-growing salmon still remains the only genetically engineered animal approved for human consumption in the United States, though the FDA did approve a drug produced in goats genetically engineered to secrete the compound in their milk, noted Gregory Jaffe, biotechnology project director for the Center for Science in the Public Interest.

Regardless of the regulatory hurdles ahead, small hog farmers are cynical about who would benefit most from these Chinese pigs, whose DNA has been altered to include a gene that helps regulate the animal's body temperature. The farmers said GE pigs would mostly serve such multinational companies as Smithfield Foods, the world's largest hog producer, which slaughters millions of pigs annually. The Chinese-owned Smithfield produces hogs bred to be leaner than pasture-raised pigs, and these lean hogs, specifically their piglets, require barns with heat lamps and heated floors to keep the newborns alive in their fragile first days.

The heating costs are not insignificant in large hog operations, where 5,000 animals may be confined under one barn roof. But just as important is the piglet mortality rate, which can range from 10 to 20 percent of newborns, some caused by cold barn conditions, said Todd See, head of the department of animal science at North Carolina State University. A pig with the ability to better regulate its body temperature might cut down on the mortality rates, See said.

Pigs are one of the few mammals without a gene to regulate body temperature, which is why pigs will burrow in hay during the winter months. To alter the animal's DNA, researchers from the Chinese Academy of Sciences in Beijing used a laboratory tool known as CRISPR to edit a mouse gene into pig cells, which were then used to create more than 2,500 embryos. The embryos were inserted into 13 female pigs, surrogates that ultimately gave birth to 12 male piglets.

The researchers noted that all 12 pigs were able to better regulate their body temperatures, while also decreasing their fat levels "without altering physical activity or daily energy demands," said a report published in the Proceedings of the National Academy of Sciences. "This study highlights the potential for biotechnology use in pig breeding to improve cold resistance and lean pork production."

One of the study's researchers, Jianguo Zhao, told NPR that the animals, slaughtered at six months, showed no sign of abnormalities from the DNA editing. He pronounced them healthy and normal. He even predicted the meat from these Bama pigs, a small to medium breed native to southern China, would taste the same as the flesh from non-modified pigs, even though the former have 24 percent less fat than the latter.

Small pig farmers sigh when they hear the argument that lean pork tastes just as good as the fattier stuff. To them, it's merely the latest hype from a hog industry that, for decades, has been obsessed with producing leaner meat – and then persuading Americans to buy more pork with marketing campaigns such as the Other White Meat ads. These smaller farmers have embraced old heritage breeds, such as Berkshires and Gloucestershire Old Spots, which are rich with fat and flavor. And they've made their own pitch to consumers: Lean pork is just inferior.

"Making them leaner is going to make them taste worse," said Gretchen Dimling, who co-owns Whistle Pig Hollow Farm in Reisterstown, Maryland, with her husband, John. Lean pork, she said, "already tastes like wet cardboard."

Bev Eggleston, co-founder of EcoFriendly Foods in Moneta, Virginia, echoed Dimling's thoughts. "It's going to be a terrible-tasting pig," he said. "I don't know about Chinese cultures, but I bet they like their old-timey pork that they've been eating for thousands of years."

These small hog farmers say GE pigs are a solution to a problem that exists mostly at large-scale operations like Smithfield's. (Smithfield did not return an email and phone call for comment.) Old heritage breeds tend to have a lot of backfat, which naturally protects them from cold weather.

"They're walruses," Eggleston said. "They don't regulate their body heat. They pack on the fat. It's not like my pigs are freezing in the winter."

On Wednesday, the Dimlings helped a sow named Dottie give birth to, as Gretchen Dimling said, 14 "non-genetically modified, healthy piglets." The barn at Whistle Pig Hollow is not heated, but a corner of the farrowing area is accessible only to piglets. A single heat lamp is trained on the corner to help keep the pigs warm. The electricity needed to power the lamp is negligible, Gretchen Dimling said.

"I don't think we've ever had one freeze to death," Gretchen Dimling said. "Piglets aren't always under [the lamp]. They'll run around and every once in awhile take a nap in the corner."

Will Harris III, the fourth-generation owner of White Oak Pastures in Bluffton, Georgia, worried about the potential effects of a genetically modified pig, the kind that may not appear for years. He equates GE pigs to the ammonium nitrate fertilizer that salesmen persuaded his ancestors to spread across White Oak farm following World War II. At first, Harris said, the fertilizer produced lush, green grass. But by the 2000s, the soil at White Oak was depleted, robbed of the nutrients needed to produce crops or grass.

"So many scientific breakthroughs that we've seen have undesirable consequences," Harris said. "We won't know for dozens of years, maybe 100 years, if there are unforeseen consequences for genetically modified animals."

Then again, these concerns, as legitimate as they may be, could amount to nothing more than unnecessary hand-wringing. North Carolina State University's See said the GE pigs in China face some formidable obstacles before ever reaching the American consumer, let alone an American farm. For starters, See isn't sure U.S. consumers are ready to chow down on pork from genetically modified hogs.

"It's probably got a bigger FDA hurdle and a bigger marketing hurdle than it may be worth" to introduce the pig to the American market, he said.