Modification and application of an in vitro assay to examine inositol phosphate degradation in the digestive tract of poultry

BACKGROUND An in vitro assay was modified to study the disappearance of inositol hexakisphosphate (InsP6) and the formation of lower inositol phosphate (InsP) isomers in the poultry digestive tract, and three experiments investigated the influence of diets with different ingredients and additives. Using the poultry diet as a matrix, the assay simulated the conditions (e.g. pH, temperature, proteolytic enzymes, water content, and retention time) of the crop, stomach, and small intestine, and extraction and analysis of InsP isomers were immediately conducted. RESULTS The assay produced highly reproducible results with coefficients of variation ≤10% for an InsP isomer concentration ≥0.4 µmol g−1 DM (n = 3), and it was sensitive to the factors that varied in the three experiments. CONCLUSION The described assay is a suitable tool that can be used to screen feed enzymes and to investigate the effects of supplements in the absence of endogenous phytases. The ease of handling and high reproducibility of the assay indicated that the assay is a rapid and feasible method that can be used to examine the degradation pathway of phytate in feed under gastrointestinal conditions.