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The genetically engineered "Enviropig" | Think Eat Act

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The solution to environmental pollution caused by intensive livestock production is not to tinker with the genes of farm animals. Pollution is a management problem that can be solved by simple changes such as altering sources of feed, reducing concentration of livestock and changing manure management methods.

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Move over, bacon. Here comes something greener.

A genetically engineered pig recently approved for limited production in Canada makes urine and feces that contain up to 65 percent less phosphorous, officials have announced.

That could be good news for lakes, rivers, and ocean deltas, where phosphorous from animal waste can play a role in causing algal blooms. These outbursts of algae rapidly deplete the water's oxygen, creating vast dead zones for fish and other aquatic life. (Related: "World's Largest Dead Zone Suffocating Sea.")

Dubbed Enviropig, the genetically altered animal cleared a major hurdle last month, when the government-run Environment Canada approved the animal for production in controlled research settings.

The new biotech pig could take years to pass U.S. and Canadian tests for commercial use and human consumption, noted Steven Liss, an environmental scientist at the University of Guelph in Ontario and a spokesperson for the project.

But the Enviropig's creators are hopeful the animal will eventually pass muster.

"This will be probably the most significant transgenic food to be approved. We're in new territory," Liss said.
The Problem With Pig Poop
Like all living things, pigs need phosphorous from their food, because the element plays a key role in the formation of bones, teeth, and cell walls as well as in a variety of cellular and organ functions.

Swine in the United States primarily eat corn, while those in Canada munch on cereal grains, including barley. But the kind of phosphorus that occurs naturally in those plants is indigestible without an enzyme called phytase, which pigs lack.

Most farmers feed their pigs this enzyme as a supplement. But ingested phytase isn't as effective at breaking down phosphorus as phytase created inside the pig would be, so a fair amount of the element gets flushed out in pig waste. That waste, in turn, can make its way into the water supply.

Enviropig would eliminate the need for added phytase, because the animal has been engineered to make its own. (Related: "Rabbits Milked for Human Protein; Drug Soon for Sale?")

Researchers spent more than a decade hunting for an enzyme in nature responsible for breaking down phosphorous, finally finding it in the genome of the bacterium E. coli. (Get a genetics overview.)

To make sure the modification would work in mammals, the team paired the E. coli genes with a mouse DNA promoter, a section of DNA that encourages replication of a specific segment-in this case the bacterial genes. Researchers then injected microscopic fertilized pig embryos with the mixture.

Early trials revealed that the bacterial enzyme was not only incorporated into the pig genome, it could be inherited by the genetically engineered pigs' offspring.

"We are now in the eighth generation of pigs, and it has been transmitted to all of those generations," said Cecil Forsberg, a University of Guelph microbiologist and lead researcher on the project.

"And from our testing, there is no change in the structure of the gene throughout those generations."

With the added genes, Enviropig is able to absorb more phosphorous from its feed, so less of the element ends up unused and excreted.
Greener Pig Also a Cost Saver?
Enviropig addresses not only environmental concerns but also societal challenges in pig farming, the University of Guelph researchers say.

In addition to cutting feed-supplement costs, Enviropig could help farmers comply with "zero discharge" rules in the United States that allow no nitrogen or phosphorous runoff from animal operations.

Right now, most pork producers meet this law by collecting pig waste in pits and lagoons until it can be treated or recycled as fertilizer-resulting in added expenses for the farmers. (Related: "Human Waste Used by 200 Million Farmers, Study Says.")

"The cost to produce animals is increasing, putting the burden on farmers in a global marketplace," project spokesperson Liss said.

Now that Enviropig has reached a milestone, pork producers will be watching to see if the transgenic animal passes safety tests with the U.S. Food and Drug Administration, noted Paul Sundberg, vice president of science and technology for the U.S. National Pork Board.

Industry professionals will also want to see a cost-benefit analysis, to be sure Enviropig will be a boon to the industry, Sundberg said.

"Pork producers are in favor of any technologies that can increase their competitiveness," he said.

So far, no transgenic animal has been approved for consumption in the United States. But in 2008 the FDA announced approval of the first human health product made from a genetically engineered animal.

The goat-derived anticoagulant, ATryn, is used for the prevention of blood clots in patients with a rare disease-causing protein deficiency.

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Gene-Altered "Enviropig" to Reduce Dead Zones?

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Move over, bacon. Here comes something greener. A genetically engineered pig recently approved for limited production in Canada makes urine and feces that contain up to 65 percent less phosphorous, officials have announced.

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A research team at the University of Guelph has developed a new line of transgenic "Enviropigs." The new line of pigs is called the Cassie line, and it is known for passing genes on more reliably. The results of this project were published ahead of print in the Journal of Animal Science.

Enviropigs have genetically modified salivary glands, which help them digest phosphorus in feedstuffs and reduce phosphorus pollution in the environment. After developing the initial line of Enviropigs, researchers found that the line had certain genes that could be unstable during reproduction or impractical in commercial use.

Scientists at the University of Guelph created the Cassie line to address these problems. In their paper for the Journal of Animal Science, they explain that the Cassie line has the same ability to digest high levels of phosphorus in plant matter.

Phosphorus is crucial for healthy growth in pigs. Unfortunately, 50 to 70 percent of the phosphorus in grain is in the form of phytic acid, a compound indigestible by pigs. Because of this, many farmers have to supplement pig diets with an enzyme called phytase. Phytase breaks down phytic acid and helps pigs digest more of the nutrient. The phytase enzyme has a hefty price tag for farmers, and the enzyme can be accidentally damaged or destroyed when farmers mix feed.

The Enviropig was created to solve this problem. The transgenic pig synthesizes phytase in its salivary glands, eliminating the need for additional supplements or enzymes in the feed. By digesting more phosphorus, the Enviropig also produces less phosphorus in its waste.

"The enzyme is secreted in the saliva and functions in a similar fashion to that of phytase included in the diet," said Dr. Cecil Forsberg, Professor Emeritus, Department of Molecular and Cell Biology at the University of Guelph and co-author of the study.

Though no studies indicate a food safety risk from genetically modified Enviropig pork, meat from the Enviropig is not yet available for human consumption. Forsberg said using Enviropigs could improve food production and the environment.

"When transgenic food animals are accepted by consumers, the Enviropig perhaps would be one of the first innovations to be introduced into swine production," said Forsberg. "We have demonstrated that the gene can be transferred by breeding through many generations in a stable fashion. Furthermore, the pigs are healthy."

Research on the Cassie line stopped in June 2012, but researchers collected semen from the pigs, and they have the option to breed new Enviropigs.

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agriculture and food; food and agriculture; biology; genetics; biotechnology and bioengineering; biotechnology; biochemistry research; food

# data[].attributes.attachment_link.description
A research team at the University of Guelph has developed a new line of transgenic "Enviropigs." The new line of pigs is called the Cassie line, and it is known for passing genes on more reliably. The results of this project were published ahead of print in the Journal of Animal Science.