Pigs account for more than 60 percent of Chinese people’s demand for meat, but they also exert major environmental pressure: fecal nitrogen from pig farms accounts for about 20 percent of the country’s total discharge of nitrogen pollutants. Pigs lack three enzymes (phytases) which block the release of nitrogen. By knock-in of the pertinent genes into genetically modified pigs, these enzymes were incorporated into the pig genome, and specifically affected the pigs’ salivary glands. As a result, fecal nitrogen and phosphorus output of the GM pigs was reduced by up to 45 percent, and the pigs showed a 14-percent improvement in their ability to absorb those nutrients.
China Bio news release, June 25, 2018