Abstract
BackgroundThis study evaluated the effects of supplemental xylanase and xylooligosaccharides (XOS) in a corn-soybean 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.ResultsXylanase 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).ConclusionIt 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.
Highlights
The application of exogenous enzymes in fibrous diets has been found to increase nutrient utilization and subsequently improve the growth performance of broilers [1, 2]
Xylanase is commonly used to improve nonstarch polysaccharide (NSP) degradation in wheat-based diets, but it is increasingly being used in corn-based diets in broilers [3, 4]
Ileal mucosa villus height (VH) and crypt depth (CD) were not affected by treatments (P > 0.05; Table 4)
Summary
The application of exogenous enzymes in fibrous diets has been found to increase nutrient utilization and subsequently improve the growth performance of broilers [1, 2]. The enhancement in digestibility and the improvement in nutrient utilization are essential for the improved growth performance. To ensure improved nutrient utilization, it requires an increased mucosal surface area for absorption, a better access of digestive enzymes to nutrients in the digesta, and increased NSP degradation in the host [5]. Exogenous enzymes like xylanase could reduce the intestinal digesta viscosity, enhance the absorption of nutrients and concurrently increase the rapidly fermentable substrates for the normal gut microbiota [6]. 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. 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
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