Measurement of true ileal phosphorus digestibility in meat and bone meal for broiler chickens.

An experiment was conducted to estimate true ileal phosphorus (P:) digestibility of 3 meat and bone meal samples (MBM-1, MBM-2: , and MBM-3:) for broiler chickens. Four semipurified diets were formulated from each sample to contain graded concentrations of P. The experiment was conducted as a completely randomized design with 6 replicates (6 birds per replicate) per dietary treatment. A total of 432 Ross 308 broilers were assigned at 21 d of age to the 12 test diets. The apparent ileal digestibility coefficient of P was determined by the indicator method, and the linear regression method was used to determine the true P digestibility coefficient. The apparent ileal digestibility coefficient of P in birds fed diets containing MBM-1 and MBM-2 was unaffected by increasing dietary concentrations of P (P > 0.05). The apparent ileal digestibility coefficient of P in birds fed the MBM-3 diets decreased with increasing P concentrations (linear, P < 0.001; quadratic, P < 0. 01). In birds fed the MBM-1 and MBM-2 diets, ileal endogenous P losses were estimated to be 0.049 and 0.142 g/kg DM intake (DMI:), respectively. In birds fed the MBM-3 diets, endogenous P loss was estimated to be negative (-0.370 g/kg DMI). True ileal P digestibility of MBM-1, MBM-2, and MBM-3 was determined to be 0.693, 0.608, and 0.420, respectively. True ileal P digestibility coefficients determined for MBM-1 and MBM-2 were similar (P < 0.05), but were higher (P < 0.05) than that for MBM-3. Total P and true digestible P contents of MBM-1, MBM-2, and MBM-3 were determined to be 37.5 and 26.0; 60.2 and 36.6; and 59.8 and 25.1 g/kg, respectively, on an as-fed basis.