Effects of addition of xylanase on growth performance, nutrient digestibility and non-starch polysaccharide degradation in broilers fed wheat-based diets

Wheat has known as an alternative source of energy in poultry diets because of a shortage of corn supply and the increase in corn price. However, its utilization efficiency is lower than that of corn because it contains more anti-nutritive factors, especially non-starch polysaccharides (NSP). Some studies suggest that the addition of xylanase in wheat-based diets can reduce the intestinal viscosity by partially hydrolyzing the NSP of wheat, resulting in improvements in nutrient digestibility and growth performance of broilers. Therefore, the focus of this study was to assess the effects of xylanase supplementation on growth performance, nutrient digestibility and non-starch polysaccharide degradation in broilers fed wheat-based diets.

A total of 280 (7-day-old) broiler Ross 308 were assigned to one of five dietary treatments including a basal diet (PC), a basal diet supplemented with xylanase (PCX) while the other three diets were wheat-based (XH: 8%, XM: 4% and XL: 2% corn replaced with wheat bran) and supplemented with 3000U/kg xylanase. 8 replicates per treatment and 7 chicks per cage were used in a randomized complete block design. Experimental diets were given to the birds from 8 to 35 days of age. The study lasted for 27 days. Body weight and feed intake were measured weekly. Ileal digesta was collected for digestibility and viscosity analysis. Collected data was analyzed for statistical significance.

The addition of xylanase at 8% in the wheat bran-based XH diet tended to improve body weights (P> 0.05) at day 35 when compared to the other diets. Significant improvements for the ADG were also noted on day 35 (P=0.026). Marginal improvements for the ADG (P=0.053; P=0.073) were also noted with the feeding of xylanase in the XH, XM and XL, when compared to the PC and PCX diets. Considering the ADFI, improvements (P< 0.05) were also noted with xylanase feeding in the XH and XL diets as at days 21 and 35. However, neither significant effects nor trends (0.05< P< 0.10) were noted for the FCR with the feeding of xylanase in the diets. The intestinal viscosity was reduced (P< 0.05) with xylanase supplementation in the PCX, XH, XM and Xl diets when compared to PC. Interestingly, the intestinal viscosity with the feeding of the XH diet with a higher wheat content of 8% was the most pronounced. The reduced intestinal viscosity could have been involved in the increased nutrient digestibility of energy (P< 0.05) at day 24 and day 35. Improved protein digestibility (P< 0.05) was only noted at day 24 with the xylanase addition in the PCX diet when compared to the other treatments.

Conclusively, xylanase supplementation in the test diets exerted an effect on indices of growth performance such as body weight, feed intake and daily weight gain of broiler chickens. It also improved nutrient digestibility for energy and protein. Particularly, the addition of xylanase in the XH diet with a higher wheat content (8%) resulted in better performance and thus is recommended.

     

Key words: broiler, digestibility, growth performance, non-starch polysaccharide, xylanase.