Measurement of true ileal phosphorus digestibility in meat and bone meal for broiler chickens using the direct method

The aim of the present study was to determine the true ileal phosphorus (P) digestibility in meat and bone meal (MBM) for broiler chickens using the direct method. Four MBM samples (coded as MBM-1, MBM-2, MBM-3 and MBM-4) were obtained and analysed for nutrient composition, particle size distribution and bone to soft tissue ratio. The total P concentration of MBM-1, MBM-2, MBM-3 and MBM-4 were determined to be 38, 60, 60 and 41 g/kg, respectively. The corresponding geometric mean particle diameter and bone to soft tissue ratio were 0.866, 0.622, 0.875 and 0.781 mm, and 1:1.49, 1:0.98, 1:0.92 and 1:1.35, respectively. Five experimental diets, including four diets with similar P concentration (4.4g/kg) from each MBM and a P-free diet, were developed. Meat and bone meal served as the sole source of Pin the MBM diets. Titanium dioxide (3 g/kg) was incorporated in all diets as an indigestible marker. Each experimental diet was randomly allotted to six replicate cages (eight birds per cage) and offered from day 28-31 posthatch. Apparent ileal P digestibility was calculated by the indicator method and basal ileal endogenous P losses, determined following the feeding of the P-free diet, were used to calculate the true ileal P digestibility. Basal ileal endogenous P losses were determined to be 354 mg/kg dry matter intake. True ileal P digestibility coefficients of MBM-1, MBM-2, MBM-3 and MBM-4 were determined to be 0.623, 0.617, 0.615 and 0.444, respectively. True ileal P digestibility of MBM-1, MBM-2 and MBM-3 were similar (P > 0.05) and higher (P < 0.05) than that of MBM-4. The present findings suggest that the direct method may be considered for use in the determination of true P digestibility in feed ingredients for poultry, but further studies are clearly needed to validate this possibility. The present data also suggest that the general assumption that Pin MBM is highly available is not valid. (C) 2016 Elsevier B.V. All rights reserved.