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This study was conducted to evaluate the effect of dietary xylanase supplementation and insoluble fiber on growth performance, microbial populations, and histomorphology of broiler chickens fed wheat-based diets. A total of 300 one-day-old male chicks were assigned in completely randomized design with a factorial arrangement 2 × 3 using 6 treatments and five replicates (10 chicks per replicate) from 1 to 42 days of age. Treatments were insoluble fiber source (none (CTL), 3 % wheat bran (WB), and 3 % rice bran (RB) ) and xylanase supplementation (with (+) and without (_) in a wheat-based diets. Dietary supplementation of xylanase with insoluble fiber resulted in a reduction of overall feed intake (FI). The body weight gain (BWG) of birds fed the CTL diet in the absence of enzyme increased compared to the enzyme-containing diet, but the opposite effect was observed at the presence of WB. The feed conversion ratio (FCR) was markedly decreased by xylanase supplementation, both independently and in combination with insoluble fiber, during the finisher phase and the entire period of experiment. Dietary supplementation of xylanase at the presence of WB and RB increased the cecal microbial population of Lactobacillus and coliforms. The duodenal pH decreased by supplementation of xylanase in CTL and RB diet. The addition of xylanase in CTL or insoluble fiber diet decreased ileal viscosity, however, it did not have effect on litter moisture. Dietary supplementation of xylanase in CTL and WB diet increased the villus height of jejunum. Supplementation of xylanase to diets containing WB and RB increased the villus height to crypt depth ratio in the jejunum. It can be concluded that xylanase supplementation in diets containing insoluble fiber, positively influenced growth performance, cecal microbial composition, and intestinal histomorphometry in broiler chickens.
Karimipour et al. (Thu,) studied this question.