Impact of corn particle size, phytate content of soybean meal, and phytase inclusion in feed on broiler growth performance, phosphorus digestibility, and bone health

Two experiments were conducted to determine the effects of coarse corn (CC), soybean meal (SBM) phytate content, and phytase on growth performance of broilers, phosphorus (P) digestibility, bone ash and strength. Experiment 1 consisted of 21-d studyin 2x2 factorial arrangement with two phytate levels: normal (NP) and low (LP) phytate and two sizes of corn particle (0% CC and 50% CC) with eight cages/treatment of nine birds/cage. Experiment 2 consisted of 35-d study with 2x2x2 arrangement, containing LP or NP-SBM, 0% or 50% CC, and 0 or 300 FTU/kg phytase. There were four pens/treatment of 16 birds/pen. In experiment 1, LP-SBM diets decreased body weight gain (BWG) and 50% CC increased feed conversion ratio (FCR) (P <= 0.05) at d-16. In experiment 2, 50% CC increased (P <= 0.05) FCR by approximately 2 points compared to 0% CC. Phytate-P digestibility in experiment 1 was lower (P <= 0.05) in LP-SBM, while total P digestibility in experiment 2 was approximately 7% higher in LP-SBM. Adding phytase improved (P <= 0.05) total P digestibility by 13% in NP-SBM and 6% in LP-SBM. Results demonstrated that inclusion of less than 50% CC should be considered. Phytase inclusion or using NP-SBM improved P digestibility; however, using LP-SBM in formulation should consider higher availability of nutrients to avoid nutrient imbalance.