Improving the nutritive value of full-fat rice bran for broiler chickens using a lipase-based enzyme preparation

Two experiments were conducted to test the hypothesis that a lipase-based enzyme preparation would increase the AME content of full-fat rice bran (FFRB) by increasing fat digestibility when fed to broiler chickens. Experiment 1 used FFRB from Australia and lasted for 35 days, while Experiment 2 used FFRB from Thailand and lasted for 14 days. Rice bran was substituted in a maize-soybean diet at levels of 90 g/kg (Experiment 1) and at 90 and 180 g/kg in Experiment 2. Total collections of excreta were used for determination of AME content and fat digestibility. In Experiment 1, the enzyme increased the AME content of FFRB between days 4-7, 18-21 and 32-35 by 6.1-16.1% (p>0.05), however this was not associated with improved far digestibility. In Experiment 2, the enzyme enhanced the AME content of FFRB between days 4-7 (10.42 vs. 9.06, p=0.107) and 11-14 (11.94 vs. 9.93, p=0.041), but again, this was not caused by increased fat digestibility. Inclusion of 180 g/kg depressed the AME content of FFRB by 7.4-11.5% (p>0.10) in conjunction with decreased (p<0.05) fat digestibility between 0-14 days of age. Improvements in bird growth with the enzyme were seen in Experiment 2 but nor in Experiment 1. Increases in AME content of FFRB per se were not caused by enhanced fat digestibility, suggesting that the side activities associated with the preparation must have acted singularly or in combination to improve AME content and bird performance. These data show that the response of FFRB to the lipase-based enzyme preparation was dependent upon the geographical origin of the rice bran and the level of FFRB substituted in the basal diet.