Factors Affecting Phosphorus Utilization in Feed Ingredients

A study was conducted to evaluate effects of feeding low phytic acid (LPA) corn, LPA soybean meal, normal corn (NC), normal soybean meal (NSBM), and phytase on nutrient digestibility and excretion. Barrows weighing about 45kg were randomly assigned to 1 of 8 dietary treatments in a 2 x 2 x 2 factorial arrangement (6 pigs/treatment). Phytase was added to the diet at 510 FTU/kg of feed, at the expense of corn starch, and all diets were formulated to provide 0.39% total phosphorus (P), 0.50% calcium, and 1.0% lysine with no supplemental inorganic phosphorus. Pigs were adapted to metabolism crates and dietary treatments for 7 days followed by a 3-day total collection of urine and feces. Total fecal DM excreted, % DM of feces, and % DM digested were not different among treatments. Fecal phosphorus excretion was reduced for pigs fed:



The low phytic acid corn and soybean meal had no effect (P > 0.11) on water-soluble phosphorus excretion. However, pigs fed diets containing phytase tended to excrete less total water soluble phosphorus than those without phytase inclusion (1.99 vs. 2.27 +/- 0.099 g/d; P < 0.066). This study demonstrates that the feeding of any combination of LPA corn, LPA soybean meal, and phytase was additive, significantly improved phosphorus digestibility and dramatically decreased phosphorus excretion to reduce the potential impacts of phosphorus from pig manure on the environment.

Hill, B.E. and co-workers. 2008. Effects of low-phytic acid corn, low-phytic acid soybean meal, and phytase on nutrient digestibility and excretion in growing pigs. J. Animal Sci. published on line November 21.