The present work was conducted to evaluate the use of xylanase and rice bran in rations supplemented with phytase for broiler chickens. In the experiment were utilized 540 one day old male Ross chicks, allocated into a completely randomized design in a 4 x 2 +1 factorial arrangement (xylanase x rice bran + control) with four replicates of 15 birds per pen. The control ration was based on corn and soybean meal without enzyme supplementation were formulated to reach the chickens nutrient requirements. The rations with the addition of rice bran also were based on corn and soybean meal were supplemented with 900 units of phytase/kg. All the rations were formulated according to Rostagno et al. (2000), except for available phosphorus and calcium in the rations containing rice bran, in which the levels were reduced (0.22% and 0.75%). Rice bran was added in 10% or 20% in the ration supplemented with four levels of xylanase (0, 200, 400 or 600 units/kg). The use of xylanase did not affect feed intake as well as any treatments tested. The chickens fed ration with 20% of rice bran shown feed intake 2.6% lower and feed conversion 2.2% better than the chickens fed ration with 10% of rice bran from 1 to 21 days. As compared with the control ration, feed intake for ration with 20% of rice bran shown lower for ration supplemented with less than 600 units/kg of xylanase and weight gain was lower without xylanase and with 20% of rice bran up to 200 units/kg of xylanase from 1 to 21 days. The best weight gain was estimated for 391 units /kg of xylanase for the ration supplemented with 10% of rice bran from 1 to 21 days and for the ration with 20% of rice bran, the optimum level of xylanase should be higher than the levels utilized in this experiment for both phases. The best results of feed conversion were estimated as 350 and 425 units/kg of xylanase from 1 to 21 days, respectively, by using rations with addition of 10 and 20% of rice bran. Accord to the data the increase of the level of rice bran in the ration also the xylanase should be supplemented in order to reduce the detrimental effects on chickens performance. Rations without xylanase, the addition of rice bran should not exceed 12%. Therefore supplementation of 400 units of xylanase per kg of ration, allow to add up to 20% of rice bran in the ration. The maximization of chickens performance fed ration with higher than 20% of rice bran should be supplementation of xylanase higher than 600 units/kg of ration.
Broiler chickens; enzymes; phytase; rice bran; xylanase
