Effects of Low Phytic Acid Corn, Low Phytic Acid Soybean Meal and Phytase on Nutrient Excretion and Nutrient Digestibility in Pigs

Purdue University 2002 Swine Research Report. Environmental concerns associated with animal agriculture are of the utmost interest to producers and regulators alike. In December 2002 the United States Environmental Protection Agency is scheduled to release new regulations that will attempt to guide manure management practices for all production levels of animal agriculture. A proposed component of the new regulations is to require a comprehensive nutrient management plan to establish a nutrient balance on each animal production unit. Within the past thirty years our animal producers have changed from small, diversified farms to larger, more concentrated operations, with a greater mass of nutrient outputs located at one site. In addition to this, the use of commercial fertilizer has steadily increased while manure has gained the perception as a waste problem instead of beneficial soil fertilizer and constituent. Thus, it becomes increasingly important to maximize nutrient uptake by the animal in an effort to reduce total nutrient output to the environment and in establishing a whole farm nutrient balance. About 85% of the phosphorus (P) in a normal corn-soybean meal diet fed to swine is not utilized because it is bound as phytate phosphate (Veum et al., 2001). Swine lack the digestive enzyme phytase, which is responsible for the release of the bound P from the phytate inositol ring; therefore, large amounts of inorganic P are commonly supplied to swine diets in an attempt to meet the P requirements of the developing pig. However, when diets are supplemented with inorganic P, large amounts of P that are unavailable to the pig (bound to phytate) are excreted and, if not properly managed, could have potential detrimental consequences on the environment. In addition to negative impacts of poorly managed P to the environment, nitrogen (N) and organic matter also threaten ground and surface water contamination with ill effects such as hypoxia, algae blooms and low dissolved oxygen levels. The objective of this study was to evaluate the effects of feeding low phytic acid (LPA) corn, LPA soybean meal and the Phytase enzyme on P digestibility and excretion with grower pigs.