In vitro assessment of enzymatic phytate dephosphorylation during digestive process of different feeds and feed ingredients

In vivo studies of the digestive process are long, expensive and difficult to rationalize, whereas in vitro systems may give more accessible insight into parts of this process. The purpose of this study was to show the ability of a three-step simulation of monogastric animals' digestive system to estimate phytate hydrolysis and how it is affected by feed composition. Several feed ingredients: wheat, maize, soybean meal and rapeseed meal and complete diets: a wheat-maize-soybean-mealbased diet, a maize-soybean-meal diet and a wheat-maize-rapeseed-meal diet were treated using an adaptation of a described in vitro digestion simulation system in the presence of increasing doses of phytase. A strong dependence of phytate hydrolysis on the feed ingredient used was obtained: phosphorus releases were 0.3, 0.8, 1.0 and 1.6 g/kg at 0 U/kg of phytase supplementation for maize, soybean meal, wheat and rapeseed meal respectively and 1.2, 2.9, 1.7 and 3.9 at 1000 U/kg of bacterial phytase. The efficacy of enzymatic dephosphorylation of phytate was found dependent on the ingredient, which can be partially explained by their initial content in myo-inositol phosphates. The in vitro simulation was proven a useful tool to assess enzymatic dephosphorylation of phytate under different conditions.