Effect of phytase and xilanase on the performance and bone characteristics of broiler chicks fed diets with rice bran

The present work was designed to verify the effect of the use of phytase and xylanase on the performance and bone deposition of minerals in broiler diets containing 15% of rice bran, low available phosphorus and without supplementation of iron, zinc, copper and manganese. The phytase utilized was the Natuphos 5000 and the xylanase Avizyme 1300. The experimental design was the completely randomized and the analysis of variance in a 4x2+1 factorial scheme. The control diet was made up of adequate levels of all nutrients without rice bran and without enzymes. The diets of the other treatments were formulated with 15% of rice bran with low available phosphorus (40% of the recommended) and without inorganic supplementation of Fe, Cu, Zn and Mn with four levels of phytase (0, 400, 800 and 1200 units/kg) with or without xylanase (1kg/t). The variables analyzed at 21 and 42 days of age were performance and ash, P, Zn, Fe, Mn and Cu in the tibia. Live weight and feed intake increased significantly with supplementation of phytase whereas feed conversion was not affected both at 21 and 42 days. The best level of phytase of 1105 and 1023 FTU/kg for better performance was reached at 21 and 42 days, respectively. The xylanase did not affect significantly live weight and feed intake. Therefore the data shown a significant improvement in feed conversion at the two ages evaluated provided by lower feed intake by the birds fed diets supplemented with xylanase. The phytase levels showed a linear increase in the contents of ash and phosphorus in the tibia and did not affect the deposition of Zn, Fe, Mn and Cu in the two studied ages. The xylanase did not have any effect on the parameters evaluated in the tibia.