Scientists Created Low-Fat Pigs by Editing Their Genes With CRISPR

Raising pigs for food is a tricky business—mostly because of their fat, the part that makes bacon so tasty. You can’t plump them up too much, because overly fat pigs are more expensive to raise. Since they’re not as efficient at burning body fat, they require more energy—in the form of heated pens and barns—to keep them warm. Yet too-skinny pigs aren’t able to regulate their body temperature properly and tend to die when temperatures drop. Farmers have to find a way to keep their pigs healthy but plump enough to produce meat.

Now, in a paper published in Proceedings of the National Academy of Sciences, researchers in China report that they have created healthy pigs with much less body fat. Using the gene editing tool CRISPR, which can precisely edit DNA, the scientists inserted a gene that helps pigs to burn fat to stay warm. It turns out that pigs don’t have this gene, which other mammals, including mice and rats, use to regulate their body temperature.

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The Chinese research team inserted a mouse version of the gene into embryonic pig cells, then coaxed those cells to generate more than 2,000 pig embryo clones that were genetically identical to each other. Female pig surrogates gestated the embryos, and 12 male piglets were born with the new gene.

The genetically modified pigs contained about 24% less body fat than pigs without the gene. The animals were bred for their meat, but it’s not clear yet whether the genetic change affected the taste or quality of the pork they produced. Autopsy of the animals at six months showed that their organs and tissues seemed to be normal.

If the results are replicated, the pigs may represent new agricultural potential: leaner pigs that don’t get cold, don’t cost as much to raise and make potentially healthier, lower-fat bacon. But don’t expect these pigs to fly in the U.S. anytime soon. Because they are genetically modified, the Food and Drug Administration (FDA) would have to approve them after being reassured that the meat they produce is safe to eat. The safety of CRISPR hasn’t been completely proven yet, either; some researchers point out that as precise as CRISPR is, it’s still not perfect. There’s always a chance that CRISPR could introduce some other unintended changes in the DNA that might have negative consequences. For now, however, the pigs are proof that it’s possible to make lower fat pork.