Lagos, V., M. Bedford, and H. H. Stein. 2022. Phytate breakdown, nutrient digestibility, plasma metabolites, and bone ash of pigs fed increasing phytase levels for a long adaptation period. 15th International Symposium on Digestive Physiology of Pigs. Animal - Science Proceedings 13(Issue 2): 174-175. Link to abstract.

Phytic acid is the main storage of P in plants, and most P in plant feed ingredients is bound in the phytate complex. Because pigs do not secrete phytase, an enzyme to hydrolyze inositol bonds in phytate, the utilization of P by pigs is very low. Addition of supplemental phytase to diets thus results in release of P and increases P utilization by pigs. However, all enzymes have a special recognition mechanism called specificity that works only with molecules that fit to active sites of the enzyme. Therefore, it is important to know how much of P is phytate-bound and how much of the P in a given diet is not phytate-bound.

Microbial phytase is usually included in diets for pigs to increase P absorption and utilization by hydrolyzing phytate within the gastrointestinal tract of pigs. High doses of phytase (i.e., > 1,000 FTU/kg) is also hypothesized to increase release of nutrients other than P due to increased degradation of phytate. A next generation biosynthetic bacterial 6-phytase (PhyG; DuPont Animal Nutrition) may increase digestibility of nutrients in diets for pigs; however, there are no data to demonstrate the efficacy of this phytase. Therefore, an experiment was conducted to test the hypothesis that the negative impact of phytate is reduced at higher phytase doses. It was also the objective of this research to test the hypothesis that inclusion of increasing levels of phytase increases bone ash and apparent total tract digestibility (ATTD) of minerals in diets containing varying phytate concentrations.