A high proportion (55 to 80%) of the phosphorus in cereal grains and oilseed meals is bound chemically in the form of phytate. The phosphorus in this form is poorly digested by pigs because they lack the enzyme (phytase) needed to remove phosphorus from the phytate molecule. Because of this, an "available" inorganic phosphorus source must be added to the diet to meet the pig's requirement for this nutrient.
Adding the enzyme phytase to the pig's diet has been shown to be an effective means of increasing the phosphorus availability from the phytate molecule in the digestive tract. When this enzyme is added, a lower dietary phosphorus concentration can be fed. Studies have indicated that the inclusion of phytase in swine diets has increased the availability of phytate phosphorus in a corn-soybean meal diet from 15% to 45% and has increased some of the trace minerals. Phytase is approved by FDA and is available in a form that can be added to swine diets.
The inclusion of the phytase enzyme in the diet will reduce the amount of phosphorus excreted in the feces. The 30 to 35% reduction in excreted phosphorus is important because environmental regulations have been proposed that will regulate swine waste application.