Dietary fiber-degrading enzyme supplementation in broilers aims at off-setting the anti-nutritive effect of non-starch polysaccharides and at promoting broiler health. Recently, we demonstrated that xylanase/glucanase addition in wheat-based diet improved nutrient digestibility, arabinoxylan fermentability and broiler growth. Conversely, maize arabinoxylan was found to be recalcitrant to xylanase action. These findings suggested that enzyme-mediated improvement of nutrient digestion and carbohydrate fermentation depended on the cereal type present in the diet, and may have contributed to broiler growth. Hence, we aimed at further investigating the link between dietary enzymes and carbohydrate fermentation in broilers, by studying the impact of enzyme supplementation in cereal-based diets, to the microbial communities in the ileum and ceca of broilers. For that purpose, 96 one-day-old male broilers were randomly reared in two pens and received either wheat-based or maize-based starter and grower diets. At d 20, the broilers were randomly assigned to one out of four dietary treatments. The broilers received for 8 d the wheat-based or maize-based finisher diet as such (Control treatments; WC, MC) or supplemented with a xylanase/glucanase combination (Enzyme treatments; WE, ME). At d 28, samples from the digestive tract were collected, and the ileal and cecal microbiota composition was determined by 16S ribosomal RNA gene amplicon sequencing. A similar phylogenetic (alpha) diversity was observed among the four treatments, both in the ileal and the cecal samples. Furthermore, a similar microbial composition in the ileum (beta diversity) was observed, with lactobacilli being the predominant community for all treatments. In contrast, both cereal type and enzyme supplementation were found to influence cecal communities. The type of cereal (i.e., wheat or maize) explained 47% of the total variation in microbial composition in the ceca. Further stratifying the analysis per cereal type revealed differences in microbiota composition between WC and WE, but not between MC and ME. Furthermore, the prevalence of beneficial genera, such as Faecalibacterium and Blautia, in the ceca of broilers fed wheat-based diets coincided with arabinoxylan accumulation. These findings indicated that fermentable arabinoxylan and arabinoxylo-oligosaccharides released by dietary xylanase may play an important role in bacterial metabolism.

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谷物类型和组合木聚糖酶/葡聚糖酶补充剂对肉鸡盲肠微生物群组成的影响

在肉鸡中添加膳食纤维降解酶旨在抵消非淀粉多糖的抗营养作用并促进肉鸡健康。最近，我们证明在小麦基日粮中添加木聚糖酶/葡聚糖酶可以提高养分消化率、阿拉伯木聚糖发酵能力和肉鸡生长。相反，发现玉米阿拉伯木聚糖对木聚糖酶的作用有抵抗力。这些发现表明，酶介导的养分消化和碳水化合物发酵的改善取决于日粮中的谷物类型，并且可能有助于肉鸡的生长。因此，我们旨在通过研究酶补充剂在谷物类日粮中的影响，进一步研究日粮酶与肉鸡碳水化合物发酵之间的联系，对肉鸡回肠和盲肠中的微生物群落。为此，将 96 只一日龄雄性肉鸡随机饲养在两个围栏中，并接受以小麦或玉米为基础的发酵剂和种植者日粮。在第 20 天，肉鸡被随机分配到四种饮食处理中的一种。肉鸡接受基于小麦或玉米的育成日粮（对照处理；WC、MC）或补充木聚糖酶/葡聚糖酶组合（酶处理；WE、ME）8 天。在第 28 天，收集消化道样本，通过 16S 核糖体 RNA 基因扩增子测序确定回肠和盲肠微生物群组成。在回肠和盲肠样品的四种处理中观察到类似的系统发育 (α) 多样性。此外，在回肠中观察到类似的微生物组成（β 多样性），其中乳酸杆菌是所有治疗的主要群落。相反，发现谷物类型和酶补充剂都会影响盲肠群落。谷物的类型（即小麦或玉米）解释了盲肠微生物组成总变化的 47%。对每种谷物类型的分析进一步分层揭示了 WC 和 WE 之间的微生物群组成差异，但 MC 和 ME 之间没有差异。此外，在饲喂小麦基日粮的肉鸡的盲肠中，有益菌属（如粪杆菌属和布劳氏菌属）的流行与阿拉伯木聚糖的积累相吻合。这些发现表明，膳食木聚糖酶释放的可发酵阿拉伯木聚糖和阿拉伯木寡糖可能在细菌代谢中起重要作用。