Enviropig
Encyclopedia
The Enviropig is the trademark for a genetically modified
line of Yorkshire pigs with the capability to digest plant phosphorus more efficiently than ordinary unmodified pigs that was developed at the University of Guelph
. Enviropigs produce the enzyme phytase
in the salivary glands that is secreted in the saliva. When cereal grains are consumed, the phytase mixes with feed in the pig's mouth, and once swallowed the phytase is active in the acidic environment of the stomach degrading indigestible phytic acid
with the release of phosphate that is readily digested by the pig.
Cereal grains including corn, soybean and barley contain 50 to 75% of their phosphorus in the form of phytic acid. Since the Enviropigs can now digest phytic acid, there is no need to include either a mineral phosphate supplement or commercially produced phytase to balance the diet. Because no phosphorus is added to the diet and there is digestion of the phytic acid, the manure is substantially reduced in phosphorus content, ranging from a 20 to 60% decrease depending upon the stage of growth and the diet consumed.
The benefits of the enviropig if commercialized include reduced feed cost and reduced phosphorus pollution as compared to the raising of ordinary pigs.
The Enviropig was developed by the introduction of a transgene construct composed of the promoter segment of the murine parotid secretory protein gene and the E. coli phytase gene. This construct was introduced into a fertilized embryo by pronuclear microinjection, and this embryo along with other embryos was surgically implanted into the reproductive tract of an estrous synchronized sow. After a 114 day gestation period, the sow farrowed and piglets born were checked for the presence of the transgene and for phytase enzyme activity in the saliva. Through breeding, this line of pigs is in the 7th generation, and the phytase trait is stably transmitted in a Mendelian fashion.
An editorial entitled "Genetically engineered meat close to your table" was published with online video and audio explaining the digestive capability of the Enviropig.
In 1940 the food system produced 2.3 calories of food energy for every calorie of fossil-fuel energy used in production. The energy cost included all aspects of production and delivery. In 2008 only one calorie of food energy at the supermarket was produced for every 10 calories of fossil-fuel energy used in production. The Enviropig is an example of how to reduce the energy requirement for meat production by eliminating the feed additive, phosphorus.
The reduction in phosphorus demand is also important due to peak phosphorus.
Developed by U of G scientists in 1999, the Enviropig excretes a less phosphorus manure and is said to be less environmentally damaging than conventional pigs. But participants in the protest said the real problem is not conventional pigs but the factory-style farms in which they are raised. Change the feeding method, Oxford County farmer Allan Slater said at the event, and you solve the waste-management issues related to industrial pig farming. The protest was organized by the Food Justice Collective, a working caucus of the Ontario Public Interest Research Group — Guelph, and was staged to coincide with a February 9, 2011 meeting in Guelph of the House of Commons standing committee on agriculture and agri-food, OPIRG-Guelph volunteer co-ordinator Andrea Rivera said.
United States Food and Drug Administration (FDA) has a Guidance Document that outlines types of data needed to assess food and environmental safety of a genetically engineered (GE) food animal:
The FDA guidance document is consistent with the United Nations Codex Alimentarius Commission regulatory guidance.
Regulatory approval of the Enviropig will be required in any country before commercialization of these pigs for human food consumption.
Genetic engineering
Genetic engineering, also called genetic modification, is the direct human manipulation of an organism's genome using modern DNA technology. It involves the introduction of foreign DNA or synthetic genes into the organism of interest...
line of Yorkshire pigs with the capability to digest plant phosphorus more efficiently than ordinary unmodified pigs that was developed at the University of Guelph
University of Guelph
The University of Guelph, also known as U of G, is a comprehensive public research university in Guelph, Ontario, Canada. It was established in 1964 after the amalgamation of Ontario Agricultural College, the Macdonald Institute, and the Ontario Veterinary College...
. Enviropigs produce the enzyme phytase
Phytase
A phytase is any type of phosphatase enzyme that catalyzes the hydrolysis of phytic acid --an undigestible, organic form of phosphorus that is found in grains and oil seeds-- and releases a usable form of inorganic phosphorus...
in the salivary glands that is secreted in the saliva. When cereal grains are consumed, the phytase mixes with feed in the pig's mouth, and once swallowed the phytase is active in the acidic environment of the stomach degrading indigestible phytic acid
Phytic acid
Phytic acid is the principal storage form of phosphorus in many plant tissues, especially bran and seeds. Phytate is not digestible to humans or nonruminant animals, however, so it is not a source of either inositol or phosphate if eaten directly...
with the release of phosphate that is readily digested by the pig.
Cereal grains including corn, soybean and barley contain 50 to 75% of their phosphorus in the form of phytic acid. Since the Enviropigs can now digest phytic acid, there is no need to include either a mineral phosphate supplement or commercially produced phytase to balance the diet. Because no phosphorus is added to the diet and there is digestion of the phytic acid, the manure is substantially reduced in phosphorus content, ranging from a 20 to 60% decrease depending upon the stage of growth and the diet consumed.
The benefits of the enviropig if commercialized include reduced feed cost and reduced phosphorus pollution as compared to the raising of ordinary pigs.
The Enviropig was developed by the introduction of a transgene construct composed of the promoter segment of the murine parotid secretory protein gene and the E. coli phytase gene. This construct was introduced into a fertilized embryo by pronuclear microinjection, and this embryo along with other embryos was surgically implanted into the reproductive tract of an estrous synchronized sow. After a 114 day gestation period, the sow farrowed and piglets born were checked for the presence of the transgene and for phytase enzyme activity in the saliva. Through breeding, this line of pigs is in the 7th generation, and the phytase trait is stably transmitted in a Mendelian fashion.
An editorial entitled "Genetically engineered meat close to your table" was published with online video and audio explaining the digestive capability of the Enviropig.
Environmental impact
Approximately 50-75% of the phosphorus present in cereal grains, corn, and soybeans is present in an indigestible compound called phytate that passes through the pig digestive tract and is enriched in the manure approx. 4-fold because the protein and carbohydrates in cereals are digested and absorbed. When manure from ordinary pigs is spread on land in areas of intense swine production, there is a build up of phosphorus in the soil. During spring run off or during a heavy rain, the phosphorus may leach into ponds, streams, and rivers increasing the phosphorus content, an essential nutrient for algal growth. With an excess of phosphorus there is increased algal growth that eventually causes a reduction in oxygen concentration in the water that results in the death of fish and other aquatic animals. Often toxins are produced by the algae and the water is no longer safe to drink. Since the Enviropigs excrete less phosphorus in the manure, there is less opportunity for pollution of water sources.In 1940 the food system produced 2.3 calories of food energy for every calorie of fossil-fuel energy used in production. The energy cost included all aspects of production and delivery. In 2008 only one calorie of food energy at the supermarket was produced for every 10 calories of fossil-fuel energy used in production. The Enviropig is an example of how to reduce the energy requirement for meat production by eliminating the feed additive, phosphorus.
The reduction in phosphorus demand is also important due to peak phosphorus.
Criticisms
Cathy Holtslander, community organizer with Saskatchewan-based Beyond Factory Farming, says an alternate way to address the problem of phosphorus pollution would be to reduce the concentration of hog-confinement facilities and the numbers of animals in them. Quote: “The problem isn't with the pigs. The problem of hog operations polluting the water has to do with the whole industrialization scale that has been developed to raise hogs.” In February 2011 protesters critiqued the enviropig in the heart of the University of Guelph, birthplace and home of the Enviropig. About 75 people, many wearing plastic snouts, warned against introducing the laboratory-developed pig into the human food chain. Protesters argued against genetically modified organisms and waved signs of protest targeting the use of public monies to fund the privately owned GMO and attacking the notion that humans have the right to modify life forms for private profit. One read: Public Funding, Private Pig. Another, read: Changing Pigs, Selling Life, a critique of the University of Guelph's Better Planet campaign slogan.Developed by U of G scientists in 1999, the Enviropig excretes a less phosphorus manure and is said to be less environmentally damaging than conventional pigs. But participants in the protest said the real problem is not conventional pigs but the factory-style farms in which they are raised. Change the feeding method, Oxford County farmer Allan Slater said at the event, and you solve the waste-management issues related to industrial pig farming. The protest was organized by the Food Justice Collective, a working caucus of the Ontario Public Interest Research Group — Guelph, and was staged to coincide with a February 9, 2011 meeting in Guelph of the House of Commons standing committee on agriculture and agri-food, OPIRG-Guelph volunteer co-ordinator Andrea Rivera said.
Regulatory requirements
On February 20 2010, the Department of the Environment of the Canadian Government determined that Enviropig is in compliance with the Canadian Environmental Protection Act and can be produced outside of the research context in controlled facilities where they are segregated from other animals. Steven Liss, associate vice-president (research services) of the University of Guelph said in February 2010 that "Applications to other federal agencies to assess the safety of Enviropigs for human food and animal feed were currently under review both in the U.S. and Canada and there is no set date when or if these reviews will conclude."United States Food and Drug Administration (FDA) has a Guidance Document that outlines types of data needed to assess food and environmental safety of a genetically engineered (GE) food animal:
- Product identification/description.
- Molecular characterization of the genetic construct introduced into animal.
- Molecular characterization of the GE animal lineage.
- Phenotypic (physiological) characterization of the GE animal.
- Stability of the new inheritable trait through generations.
- Food, feed and environmental safety.
- Effectiveness of the new trait/claim validation.
- Post-approval responsibilities.
The FDA guidance document is consistent with the United Nations Codex Alimentarius Commission regulatory guidance.
Regulatory approval of the Enviropig will be required in any country before commercialization of these pigs for human food consumption.