Comparison of gamma-Irradiation and enzyme supplementation to eliminate antinutritional factors in rice bran in broiler chicken diets

A study was conducted to evaluate the effect of gamma irradiation and enzyme supplementation of crude rice bran in broiler chicken diet and their effects on growth performance, carcass characteristics, intestinal microbial population, and blood profile in broiler chickens. A total of 144 one-day-old Ross 308 broiler chickens were weighed and assigned to 3 dietary treatments with 4 replicates (floor pen) of 12 broiler chickens per pen. Dietary treatments consisted of a basal diet formulated to contain 15% crude rice bran (with or without enzyme supplementation) and the diet containing 15% gamma-irradiated rice bran. The chemical changes of crude and gamma-irradiated rice bran were determined before feeding experiment. At the end of the experiment (d 42), growth performance, ileum microflora, and blood profile in broiler chickens were determined. Proximate composition of rice bran was not affected by gamma irradiation, but the contents of phytic acid and trypsin inhibitor decreased (up to 98%; P<0.05). The use of gamma-irradiated rice bran improved (P < 0.05) the body weight gain than crude rice bran. Moreover, broiler chickens on gamma-irradiated rice bran treatment had greater (14.9%) body weight gain compared to the enzyme supplementation. Although, none of the treatments had a major effect on the carcass percentage, the breast percentage (22.4%) increased (P < 0.05) because of the enzyme supplementation compared to those (18.5%) of broiler chickens on crude rice bran diet. The relative weight of liver and abdominal fat pad decreased (P < 0.05) by feeding of gamma-irradiated rice bran than the enzyme supplemented diet. Lower numbers (P < 0.05) of salmonella were found in the ileum of broiler chickens fed gamma-irradiated rice bran when compared to the use of the enzyme supplemented diet. Blood profile was not affected by the treatments. The results indicated that gamma irradiation could be a more effective method to reduce the content of antinutritional factors in crude rice bran than enzyme supplementation and improve growth performance and health of broiler chickens.