The piglets were bred by knock-in of gene UCP1, coding for a mitochondrial brown fat uncoupling protein, which plays an important role in maintaining animal body temperature and energy balance. The ancestors of modern domestic pigs lost the UCP1 gene 20 million years ago. In the studies by ZHAO Jianguo and his team, the UCP1 gene was added to the genome of pig fibroblasts through genetic editing tools, more than 2,500 transgenic pig embryos were cultivated, and embryos were implanted into 13 surrogate sows, of which three sows beame pregnant and produced 12 male piglets. Compared to wild-type pigs, the transgenic pig’s body temperature regulation ability was significantly enhanced, fat production rate and fat thickness was reduced by 24 %, and the amount of lean meat was significantly increased.

China Bio news release, October 25, 2017