Phytic Acid Chemistry: Influence on Phytin-Phosphorus Availability and Phytase Efficacy1

Poultry diets are primarily composed of seed-based ingredients and contain a high proportion of their P in the phytic acid molecule, making this P poorly available. Phytic acid (IP6) is a highly reactive acidic compound that readily binds mineral cations, and in this complexed form is called phytin. The chemical characteristics of IP6 influence exogenous (diet) and intestinal phytase efficacy and the availability of both phytin-P (PP) and any minerals bound to IP6. Research has shown that minimizing IP6-mineral complexes in the digesta of poultry can lead to increased PP availability in the absence of dietary phytase, as well as increased efficacy of dietary phytases. Understanding these binding interactions and how they influence the efficacy of different phytases can provide a valuable tool in choosing when to use phytase and what phytase to use under different situations. This understanding can provide the foundation for developing new methods, as well as minimizing the cost and maximizing efficacy of current methods, to reduce the amount of P excreted by poultry.