EFFECTS OF ENZYME SUPPLEMENTATION AND IRRADIATION OF RICE BRAN ON THEPERFORMANCE OF GROWING LEGHORN AND BROILER-CHICKENS

Three experiments investigated the effects of different concentrations of a crude enzyme preparation (RM-1) and rice bran from two sources ( China and Malaysia) on the performance of growing Leghorn and broiler chicks when added to a wheat or a corn soya-bean meal basal diet. In t he first experiment rice bran from Malaysia was also irradiated. In th is experiment enzyme supplementation of the wheat-basal diet containin g 400 g kg(-1) Malaysian rice bran improved (P < 0.05) weight gains up to 9.6% and feed to gain ratio up to 5.4% while irradiation of rice b ran at moderate (10 kGy) and high 50 (kGy) doses had no effect (P > 0. 05) on these parameters, Chinese rice bran in contrast to Malaysian ri ce bran did not respond to enzyme treatment (P > 0.05), Similar improv ements were obtained in the second experiment with RM-I addition to th e corn basal diet containing 250 and 500 g kg(-1) Malaysian rice bran, but not when added to the corn diet without rice bran. In addition, r ice bran did not have any deleterious effects (P < 0.05) on growth and feed conversion efficiency of Leghorn chicks when incorporated into d iets without enzyme supplementation. In contrast to the results with L eghorn chicks, the performance of broiler chicks was depressed(P > 0.0 5) when 250 and 500 g kg(-1) Malaysian rice bran was added to the diet . Chicks fed the diet containing 500 g kg(-1) rice bran compared to th ose fed the control diet had decreased body weight gains (17%) and inc reased feed to gain ratios (11%), relative weights of the gastrointest inal tract (40%), and incidence of vent pasting (from 0 to 67%). Enzym e addition (10 mg kg(-1)) to the 500 g kg(-1) rice bran diet improved (P < 0.05) the feed to gain ratio (4%), and reduced the size of the ga strointestinal tract (7%) and the incidence of vent pasting (from 67 t o 33%). These studies indicate that high concentrations (400-500 g kg( -1)) of rice bran can be added to the diet of Leghorn chicks, at least over a relatively short period of time, without a deleterious effect on performance while as low as 250 g kg(-1) rice bran in the diet can depress broiler chick performance. The crude enzyme when added to diet s containing rice bran produced equivocal results in chicks as it impr oved performance with one rice bran but not the other. (C) 1997 Elsevi er Science B.V.