Inside a fortress-like megafarm on the outskirts of Beijing, dozens of pink-and-black pigs forage and snooze, unfazed by the chilly spring air. These experimentally bred hogs are fortified with a gene for regulating heat, buffering them against northern China's hypothermia-inducing winters.

The gene that researcher Jianguo Zhao inserted into the pigs' DNA is among dozens of examples of genetic engineering underway in China—and in rival laboratories across the world—to create super pigs. For years, the quest was for better-tasting, stronger, and faster-growing swine. Now, in the wake of a devastating global outbreak of African swine fever, the more crucial need is to safeguard food security, and keep hogs alive.