The addition of fitase enzyme (500FTU kg-1) was evaluated, in diets of different particle size (Average Geometric Diameter - AGD) for broiler chicken at the initial phase. Birds were distributed in a totally randomized experimental design, in factorial model 2 (AGD - 680 µm and 430µm) x 2 (enzyme - with or without Fitase). Diets with fitase inclusion presented a reduction of 10.5% of Ca and 22% of P compared to basal diet without fitase. Performance was evaluated (feed intake, weight gain and feed conversion), the metabolisability coefficient of the dry matter, net protein, net energy and also biodisponibility coefficient, calcium and phosphorus. Birds that received diets with AGD 680µm presented greater weight gain (798g) and better feed conversion (1,330kg kg-1) when compared to birds fed with diets of DGM 430µm (780g and 1,390kg for weight gain and feed conversion, respectively) (P<0.05); higher metabolisability of protein and biodisponibility coefficient of calcium and phosphorus. The use of fitase, in diet with reduction of Ca and the P, promoted a bird's similar performance to basal diets, as well as it improved the metabolisability coefficient of protein and biodisponibility of calcium and phosphorus in the diets of smaller mash. In conclusion, feed conversion is improved when smaller particle size diets are used. Utilization of fitase increases the efficiency of use of nutrients in the ration and improves broiler chicken performance.
chicken; particle size; performance; phytase