Reducing the pork industry’s carbon footprint

Reducing the pork industry’s carbon footprint
May 29, 2018

Pigs that can better digest nutrients could help to lower the sector’s environmental impact

By Kate Ayers
Staff Writer

Giving pigs the ability to digest the nitrogen and phosphorus in their feed could help to reduce feed waste and nutrient release.

A large amount of pig feed is wasted because of the animals’ inability to digest nitrogen (N) and phosphorus (P). These two nutrients are eventually released through manure, and may enter the air and water sources, an eLife article said last week. 

“Pigs release harmful amounts of these nutrients as they lack the microbial enzymes that break down phytate – the main source of nitrogen and phosphorus – and types of fibre called non-starch polysaccharides,” Xianwei Zhang, a postdoctoral researcher at the South China Agricultural University, said in the article.

“We suggest that making up for the pigs’ deficiency in these enzymes – ß-glucanase, xylanase and phytase – will benefit the pork industry by increasing the animals’ feed use and reducing their nutrient emissions.”

Zhang and his colleagues inserted the three enzymes into the genetic material of pigs. The enzymes were expressed in the pigs’ salivary gland, facilitating the digestion of phytate and non-starch polysaccharides to begin in the mouth, the article said.

"We used a piggyBac transposon system, which can mediate the integration of foreign DNA fragments (expressing the required enzymes) into the host genome," Zhenfang Wu, a professor at the South China Agricultural University, said in an email statement to today.

Previous research has looked into this method for reducing P levels in manure. In this study, researchers aimed to enhance pigs’ digestion of grain and examine the levels of both P and N in the manure. 

The animals studied could digest these nutrients, as well as other important nutrients, and thus had lower nutrient release from their manure, the feeding trial results indicated.

Each genetically modified pig could, on average, save 26.8 kilograms of feed. This figure translates into feed savings of about 32.16 million tons per year worldwide, Wu said. 

“During our research, we saw that these pigs also grew faster and produced lower-N/P manure. Use of these pigs could therefore increase the pork industry's productivity and reduce its environmental pollution," he said to

“The use of genetically modified pigs and other animals in food production, both in China and globally, is restricted by current policy,” Wu said in the article.

“However, our findings indicate that these pigs are promising resources for improving feed efficiency and reducing the carbon footprint of the pork industry.”

The full study can be found here.

Updated May 30, 2018

Nicole Neily/GettyImages /E+ photo

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