Reducing Phosphorus Excretion in Broilers, Pigs and Turkeys

Several experiments were conducted at the University of Kentucky to compare diets containing normal corn and soybean meal to diets containing low-phytate corn and low-oligosaccharide soybean meal with and without supplemental phytase (Natuphos®, BASF; 75) units/kg) on phosphorus excretion in chicks and pigs. Pioneer Hi-Bred International provided the low-phytate corn and low-oligosaccharide soybean meal. The normal corn, low-phytate corn, normal soybean meal and low-oligosaccharide soybean meal contained 0.25, 0.26, 0.70 and 0.77 percent total phosphorus and 0.05, 0.17, 0.22 and 0.55% non-phytate phosphorus, respectively. Diets were formulated to demonstrate the effects of the genetically altered ingredients and effects of phytase additions. In the chick studies, the results indicated that 750 units/kg of phytase converted approximately one-third of the unavailable phosphorus in both types of corn-soybean meal diets to an available form. Feeding the low-phytase corn and low-phytate with phytase reduced total phosphorus excretion by 60 percent and soluble phosphorus by 72 percent without negatively impacting chick performance or bone traits.

In the pig experiments, the apparent phosphorus digestibility was increased by both feeding low -phytate diets and phytase additions. Most significant was the observation that total phosphorus excretion was decreased by 41 percent when phytase was added to the normal corn-soybean meal diet; by 55 percent when the low-phytate diets were fed; and by 73% when phytase was included in the low-phytate diets. Soluble phosphorus in swine excreta, as expressed as a percentage of the total phosphorus was increased by both phytase and low-phytate feed ingredients, however, the total daily soluble phosphorus was not affected by treatment. These experiments demonstrate that including phytase in the diet or can modify the phosphorus utilization and phosphorus levels in manure of chicks and pigs by genetically modifying the corn or soybean.

Xavier, E.G. and co-workers. 2004. Effects of phytase on the bioavailability of phosphorus in diets containing conventional or low-phytate corn and soybean meal for chicks. Poster W34, p321 of the 2004 Joint Annual Meeting abstracts.

Xavier E.G. and co-workers. 2004. Performance and phosphorus excretion of chicks fed conventional or low-phytate corn-soybean meal diets without or with phytase. Presentation #296, p150 of the 2004 Joint Annual Meeting abstracts.

Xavier E.G. and co-workers. 2004. Phosphorus excretion of pigs fed conventional or low -phytate corn-soybean diets without or with phytase. Presentation #409, p253 of the 2004 Joint Annual Meeting abstracts.