Phytate degradation in broilers as affected by dietary phytate and non-phytate phosphorus content

Broilers have the intrinsic capacity to degrade dietary phytate, thereby increasing precaecal phosphorus digestibility (pcdP). Insight in the extent and mechanism of phytate-P (PP) degradation is necessary to evaluate the contribution to the P-supply of the birds. An experiment was performed to determine the interaction of dietary PP and non-phytate P (nPP) content on pcdP in broilers, using the WPSA (2013) protocol for determination of P availability in poultry. A total of 756 day-old Ross 308 male broilers were obtained from a commercial hatchery and at d14 randomly allocated to 72 floor pens (0.96 m2). All birds received a commercial starter diet between d0 and 14. Experimental diets were provided from d14 onwards, and ileal digesta were collected on d23 and 24. Phosphorus (P)In total 12 different diets were pro-vided, varying in dietary PP and nPP content. In low PP diets, pcdP of monocalcium phosphate (MCP) was 88% and remained constant over a large range of dietary P contents (2-6 g/kg). In soybean meal (SBM) based high PP diets, pcdP of MCP was 47% over a large range of inclusion levels (total P 3-7 g/kg). In SBM-based high PP diets, PP degra-dation linearly decreased from 96 to 68% with increasing dietary nPP content. It was concluded that broilers are highly capable to regulate pcdP by increasing PP degradation under conditions of low nPP supply. These findings have to be taken into account in studies that determine pcdP of dietary ingredients.