Genetically modified pigs could cut carbon footprint of pork, study suggests
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According to research carried out in China, the genetic modification of pigs to help them digest their nutrients could help reduce the carbon footprint of the pork industry.
Setting aside animal products is often cited as one of the most impactful changes a person can make to protect the environment. For those not quite ready to give up their sausages and bacon, the use of genetic modification in the meat industry could play a smart part in reducing the carbon footprint of their food.
While pigs, cows and other domesticated animals are farmed around the world for their meat, hide and other parts, there are concerns that meat farming is a major contributor to climate change, due to the high carbon emissions associated with rearing animals for consumption. One aspect of this relates to the inefficiency associated with feeding these animals; pigs are unable to digest key nutrients in their feed – nitrogen and phosphorus – meaning that a large amount of their food is wasted, and these pollutants are subsequently released into the environment through the pigs’ faeces.
Given that global pig production is at 1.2 billion per year and growing, a small genetic change could have a major environmental impact.
“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,” said Xianwei Zhang, a PhD student at the South China Agricultural University. More than half of the world’s pigs are farmed in China.
“We suggest that making up for the pig’s deficiency in these enzymes – β-glucanase, xylanase and phytase – will benefit the pork industry by increasing the animals’ feed use and reducing their nutrient emissions.”
In order to see whether genetically modifying pigs to better digest their feed, Zhang and his colleagues transplanted the three deficient enzymes – secreted by microbes – into the genome of pigs. The enzymes were optimised to thrive in the digestive tract of pigs, and to be expressed in the salivary gland. This allowed for fibre and phytate – the main form in which phosphorus is stored in pig feed – to be digested, beginning in the mouth.
Previous studies showed promising results, suggesting that pigs modified to produce phytase in their saliva had reduced levels of phosphorus in their manure. This study confirmed that the genetically modified pigs were able to digest the nutrients in their feed, and consequently grew faster while producing lower carbon emissions. Meanwhile, the pigs remained unchanged in terms of mood, behaviour, reproduction and physiology.
“The use of genetically modified pigs and other animals in food production, both in China and globally, is restricted by current policy. However, our findings indicate that these pigs are promising resources for improving feed efficiency and reducing the carbon footprint of the pork industry,” said Professor Zhenfang Wu, senior author of the study.