EnviroPigs excrete out 30 to 60 percent less phosphate. Why is this important? Well, Yorkshire pigs (one of the most common pig breeds on market for slaughter) excrete waste that includes very high phosphorus content. This is from eating their normal diet which are cereal grains including corn, soybean and barley. Furthermore, the pigs are unable to fully digest phosphorus that enters their bodies. The pig manure is then used on crops as fertilizer because plants need phosphorus to grow but then the excess manure runs off to the irrigation sources such as rivers and lakes. Since the manure contains high phosphorus content, it enables algae to bloom in the water and with too much phosphorus, the algae growth would be too excessive. When they die, it takes up oxygen in bodies of water, creating "dead zones" where fish and other aquatic life cannot survive and this is the leading cause of fish kills. In North Carolina, year 1995, 10 million fish died and it was blamed on pig manure. .
This problem led to the creation of "EnviroPigs." In 1995, a group of scientists in the University of Guelph, Ontario, Canada, led a project to solve this problem using Yorkshire pigs, genetically modifying them and turning them into EnviroPigs. Their first trial was on a pig named "Wayne." Their goal was to genetically modify the pig to excrete less phosphorus so they combined an E. coli's phytase gene which is an enzyme that breaks down phosphorus with a segment of mouse parotid secretory protein promoter gene sequence which controls the production of proteins produced in the saliva gland. These genes are then inserted into a fertilized pig embryo by pronuclear microinjection. The embryo is then surgically implanted into the reproductive area of a female pig. When the piglet is born, it is born with saliva glands that can break down phosphorus.
There are, obviously, environmental benefits to this solution which is less phosphorus pollution made by pigs.