Effect of two different dietary endo-1,4-β-xylanases on growth performance, intestinal histomorphology, caecal microbial population and short-chain fatty acid composition of broiler chickens

Effects of two different dietary xylanases on broiler performance and gut integrity were determined. Totally, 7600-d-old Ross-308 chicks were used for 41 d. Chicks were randomly assigned to 4 dietary treatments with 10 replicates (95 males, 95 females per replicate); they were: positive control (PC) based on Ross 308 nutrient specification; negative control (NC) with less ME (80 kcal/kg), crude protein and amino acids compared to PC; NC + AO with addition of xylanase derived from Aspergillus oryzae (AO); NC + TB with addition of xylanase derived from Trichoderma bisset (TB). Birds fed on PC diet significantly (p < 0.05) had higher final body weight (BW) and body weight gain (BWG) compared to other treatments. The final BWG and feed conversion ratio (FCR) were not fully compensated with the addition of the enzymes compared to PC, and FCR was found significantly (p < 0.05) higher in birds fed on diets NC + AO and NC + TB. However, dietary xylanase significantly improved FCR, villus surface area and total goblet cell number in NC + AO and NC + TB birds compared to NC. Xylanase supplementation significantly increased the concentrations of branched-chain fatty acid (BCFA) and total caecal short-chain fatty acid (SCFA) (p < 0.05). Furthermore, both xylanases increased lactobacillus count (p < 0.05). Dietary treatments had no effect on carcase parameters and mortality rate. In conclusion, along with improving performance parameters, the inclusion of xylanase enzymes with nutrient matrix value in broilers' diet may ameliorate intestinal morphology, stimulate caecal microflora and increase caecal SCFA concentrations, but nutrient contribution of both enzymes seems overestimated.HIGHLIGHTSDietary xylanase could not compensate the final BWG and FCR compared to positive control.Dietary xylanase increased villus surface area and total goblet cell number.Dietary xylanase increased the concentrations of branched-chain fatty acids and total caecal short-chain fatty acid.