Effects of dietary xylanase supplementation on performance and functional digestive parameters in broilers fed wheat-based diets

This experiment was conducted to evaluate dietary xylanase supplementation in broilers wheat-based diets on performance and functional digestive parameters including ileal digesta viscosity, apparent ileal digestibility, intestinal morphology and microflora, digestive enzyme activities, and excreta odor content. A total of 600 1-day-old Ross 308 male broilers with an initial average BW of 45 +/- 0.6 g were randomly allotted into 4 treatments with 10 replicate pens per treatment and 15 broilers in each pen for 35 d. The 4 dietary treatments were wheat-based diets and supplemented with 0, 1,875, 3,750, and 5,625 XU/kg xylanase. Xylanase supplementation improved (linear, P < 0.05) the body weight gain and decreased (linear, P < 0.05) the feed conversion ratio during d 1 to 18 and for the duration of the experiment. Dietary supplementation of xylanase led to a decrease (linear, P < 0.01) in ileal digesta viscosity. The apparent ileal digestibility of dry matter (DM), crude protein (CP), gross energy, and most amino acids (with the exception of Ile, Phe, Asp, Glu, and Pro) were increased (linear, P < 0.05) by xylanase supplementation. Increasing the dietary xylanase levels improved (linear, P < 0.05) the villus height and the ratio of villus height to crypt depth of the duodenum, jejunum, and ileum. In addition, inclusion of xylanase increased (linear, P < 0.05) the Lactobacillus numbers in the ileum and cecum, while decreased the ileal E. coli counts (linear, P < 0.01) and cecal E. coli populations (linear, P < 0.01; quadratic, P < 0.05). There were no significant differences (P > 0.05) in trypsin, amylase, and protease activities of small intestine among dietary treatments. Furthermore, xylanase supplementation reduced excreta NH3 (linear, P < 0.05; quadratic, P < 0.05) and total mercaptan (R. SH) (linear, P < 0.01) concentration. Taken together, dietary xylanase supplementation in broilers wheat-based diets had beneficial effects on growth performance, apparent ileal digestibility of nutrients, intestinal morphology, and microflora balance. Furthermore, the xylanase could reduce the ileal digesta viscosity and excreta odor contents.