Mathai, J. K., R. C. Sulabo, J. L. Usry, B. W. Ratliff, D. M. McKilligan, and H. H. Stein. 2011. Standardized total tract digestibility of P in dried fermentation biomass, Peptone 50, and P.E.P. 2 Plus fed to weanling pigs. J. Anim. Sci. 89(E-Suppl. 1):85 (Abstr.) Link to abstract (.pdf)

Almeida, F. N. and H. H. Stein. 2011. Standardized total tract digestibility of P in blood products fed to weanling pigs. J. Anim. Sci. 89(E-Suppl. 2):120 (Abstr.) Link to abstract (.pdf)

Corn contains approximately 0.26% phosphorus, but most of this phosphorus is bound to phytic acid, or phytate, and thus is not bioavailable to pigs because they lack the enzyme phytase. Corn-based diets can be supplemented with inorganic phosphorus to help meet pigs' phosphorus needs; however, rising costs of inorganic phosphorus makes this approach increasingly uneconomical. Helping pigs digest more of the phosphorus that naturally occurs in the diet could provide a cost-effective alternative to inorganic phosphorus supplementation while also helping to reduce the environmental burden of excreted phosphorus. An experiment was conducted to determine how adding graded levels of microbial phytase affected the standardized total tract digestibility (STTD) of phosphorus in corn and corn co-products. From these data, regression equations were developed to predict the response to adding different levels of phytase to each ingredient.

The majority of phosphorus in conventional soybean meal is bound in the phytate complex. Pigs do not secrete the phytase enzyme, so phytate-bound phosphorus is not digested and is excreted in the feces. Not only does this deprive pigs of an essential nutrient, but excessive phosphorus excretion can contribute to environmental problems as well.

Addition of microbial phytase is one strategy for increasing the digestibility of phosphorus in soybean meal. Another potentially effective strategy is to feed fermented soybean meal.  Fermentation may result in hydrolysis of phytate and release of phytate-bound phosphorus, thus making more phosphorus available to the pig.

Stein, H. H. 2010. Nutrient and energy utilization by swine. Pages 31-42 in Proc. 26^th annual North Carolina Swine Nutrition conference, Nov. 10, 2010. Raleigh, NC. Link to full text (.pdf)

Kim, B. G., J. W. Lee, and H. H. Stein. 2010. Energy concentration and phosphorus digestibility in milk products fed to weanling pigs. J. Anim. Sci. 88(E-Suppl. 3):90 (Abstr.) Link to abstract (.pdf)

Goebel, K. P. and H. H. Stein. 2010. Phosphorus and energy digestibility in enzyme treated soybean meal. J. Anim. Sci. 88(E-Suppl. 3):86 (Abstr.) Link to abstract (.pdf)

Pedersen, C. and H. H. Stein. 2010. Effects of liquid and fermented liquid feeding on energy, dry matter, protein and phosphorus digestibility by growing pigs. Livest. Sci. 134:59-61. Link to full text (.pdf)

Almeida, F. N. and H. H. Stein. 2010. Effects of graded levels of phytase on the apparent and standardized total tract digestibility of phosphorus in corn and corn co-products. J. Anim. Sci. 88(E-Suppl. 2):378 (Abstr.) Link to abstract (.pdf)