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Enviropig to the Rescue
Genetically engineering environmentally friendly pork
By Marni Ginther
From an environmental standpoint, there’s plenty wrong with the American food system. For one, our practice of raising large quantities of animals in high concentrations disrupts natural cycles and contributes to pollution. But what if you could change the genetic makeup of these animals to reduce the adverse environmental effects of raising thousands of animals within just a few square miles? University of Minnesota animal geneticist Scott Fahrenkrug shared with digest one example of how this is possible.
Meet the Enviropig. Animal scientists at the University of Guelph in Canada created a type of transgenic pig that is more environmentally friendly to raise than normal pigs. Transgenics, Fahrenkrug explains, refers to the process of taking a gene from one animal and putting it into a different animal that didn’t originally possess that gene.
So the situation is like this: pigs naturally produce phosphorus in their manure. Since we raise pigs and other livestock in concentrated areas, their manure gets concentrated in large “manure lagoons”—and so does all that phosphorus. Those high phosphorus levels can seep into water supplies and cause an overgrowth of algae that deprives the aquatic ecosystem of oxygen and kills fish and other wildlife. To reduce this effect, farmers currently mix an enzyme into pigs’ feed that reduces phosphorus levels in their manure. The enzyme is called phytase. To produce it, you have to grow lots of fungus, then isolate the phytase from the fungus, then package and ship it to farmers. In addition to the phosphorus problem, that process adds its own carbon footprint to the pork raising industry.
The Guelph researchers found a way to make pigs with a gene that allows them to produce that phosphorous-fighting enzyme all on their own in their salivary gland. They took a gene from the fungus that produces the phytase, injected it into pig embryos and implanted the embryos in a mother pig. The result: pigs whose saliva contains the same phytase that farmers have been mixing with feed. It does the same work breaking down phosphorus in the pigs’ digestive system yet leaves no carbon footprint.
“It doesn’t mean the pigs are like fungus, it just means they can now make one more enzyme than they normally would,” Fahrenkrug says. “And they make it in one place in their body: their salivary gland.”
Studies show about a 60-percent reduction in the phosphorus excretion in the manure of the Enviropigs. Despite that success, some people see the whole process as meddling with nature, Fahrenkrug says. “I know there is no risk to having that gene in the salivary gland of a pig, because we feed these pigs the same stuff anyway,” Fahrenkrug says. “But right now, because of people’s perception about transgenics, it looks like it will be some time before we have a transgenic animal product on the market.”