Effects of supplemental xylanase and xylooligosaccharides on production performance and gut health variables of broiler chickens

Background: This study evaluated the effects of supplemental xylanase and xylooligosaccharides（XOS） in a cornsoybean meal（SBM）-based diet on growth performance and intestinal health of broilers. A total of 288 day-old chicks（Cobb 500） were allocated to 36 floor pens（8 birds/pen） equally in 9 dietary treatments in a 3 × 3 factorial arrangement. The treatments were combinations of 3 levels of xylanase（0, 0.005% and 0.01% Econase XT） and 3 levels of prebiotics（0, 0.005% and 0.01% XOS） added to basal mash diets formulated in three phases（starter, d 0–14; grower, d 15–28; finisher, d 29–42）. The feed intake and body weights were recorded weekly. On d 42, ileal sections were collected for histomorphometric and gene expression analysis, and cecal content was collected for determining short-chain fatty acids（SCFA） and microbiota.Results: Xylanase linearly（P ＜ 0.01） increased the average daily gain（ADG） in both the finisher and total period and the final body weight gain（FBWG, 2940 ＆ 2932 vs. 2760 g） of broilers. XOS did not significantly increase either ADG or FBWG（P ＞ 0.05）. Supplemental xylanase and XOS did not affect average daily feed intake and feed conversion ratio（P ＞ 0.05）. Xylanase and XOS did not change villus height（VH） or crypt depth（CD） ratio（P ＞ 0.05）. However,xylanase exhibited a trend（P = 0.097） on VH:CD ratio. The inclusion of 0.01% XOS without xylanase increased the level of IL-10（a marker of anti-inflammatory cytokine） and IL-4（a T-cell differentiation cytokine） genes compared with control（P ＜ 0.05）. The acetate production was increased by xylanase（P ＜ 0.01） and XOS（P ＜ 0.05） without an additive effect. Xylanase increased total SCFA（P ＜ 0.01） while XOS had a tendency to increase（P = 0.052）. Alpha and beta diversity of microbiota among treatments were not different（P ＞ 0.05）. However, the mean proportion of family Ruminococcaceae was increased by the supplemental 0.01% xylanase（P ＜ 0.01）.Conclusion: It can be concluded that XOS can enhance cecal fermentation, while xylanase can increase the body weight gain along with the fermentation metabolites in the ceca of broilers fed the corn-SBM-based diet but the effects may not always translate into an improved mucosal absorptive capacity and a better feed efficiency.