GM food makes pigs more environmentally friendly

A new pig diet made from genetically modified corn with higher levels of a digestible form of phosphorus could cut down on the level of phosphorus ending up in manure, say scientists.


In the US, pigs produce more than 15 million tonnes of manure each year, containing an estimated 460,000 tonnes of phosphorus, a considerable potential pollution risk, say the researchers. Though pigs require a certain amount of phosphorus in their diets, most of the element in corn and soybeans is in the form of phytate which pigs are unable to digest.

The new genetically modified corn contains higher levels of phosphorus that is digestible to pigs. “We realise that what we put into an animal affects what comes out, so we changed what we’re putting in,” said Swine Nutritionist, Gary Allee. “Rather than attempting to treat the current phosphorus levels in manure, our approach is to reduce the levels before we reach the treatment process.”

“Only 10 to 15% of the phosphorus in standard varieties of corn is digestible by pigs,” said Allee. “However, about 60% of the phosphorus in the genetically modified variety is digestible by pigs, which allows producers to supplement less inorganic phosphorus. The result is less phosphorus ends up in the manure.”

Results from testing has shown that the new corn can reduce phosphorus excretion by 30 to 40%, and does not impair pig growth.

According to Allee, the new variety of corn could also be used to reduce phosphorus excretion from poultry.

The research is part of a co-operative project involving a number of US research institutions including North Carolina State University, Purdue University, Michigan State University and Oklahoma State University.

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