Anti-nutritional compounds such as non-starch polysaccharides (NSP) are present in viscous cereals used in feed for poultry. Therefore, exogenous carbohydrases are commonly added to monogastric feed to degrade these NSP. Our hypothesis is that xylanase not only improves laying hen performance and digestibility, but also induces a significant shift in microbial composition within the intestinal tract and thereby might exert a prebiotic effect. In this context, a better understanding on whether and how the chicken gut microbial population can be modulated by xylanase is required. To do so, the effects of dietary supplementation of xylanase on performance, apparent total tract digestibility (ATTD) and cecal microbiome in laying hens were evaluated in the present study. A total of 96 HiSex laying hens were used in this experiment (3 diets and 16 replicates of 2 hens). Xylanase was added to the diets at concentrations of 0, 45,000 (15 g/t XygestTM HT) and 90,000 U/kg (30 g/t Xygest HT). The diets were based on wheat (~55%), soybean and sunflower meal. The lowest dosage, 45,000 U/kg, significantly increased average egg weight and improved feed efficiency compared to the control treatment (P<0.05). Egg quality parameters were significantly improved in the experiment in response to the xylanase addition. For example, during the last 28 days of the trial, birds receiving the 45,000 U/kg and the 90,000 U/kg treatments exhibited an increase in Haugh units and albumin heights (P<0.05). Compared with the control, the ATTD of organic matter and crude protein were drastically improved in the 45,000 U/kg treatment group (P<0.05). Furthermore, gross energy and the ATTD of crude fat were improved significantly for birds fed 90,000 U/kg group compared to the control. Importantly, 16S rRNA gene analysis revealed that xylanase at 45,000 U/kg dosage can exert a change in the cecal microbiome. A significant increase in beneficial bacteria (Bacilli class; Enterococcaceae and Lactobacillales orders; Merdibacter, Enterococcus and Nocardiopsis genera; Enterococcus casseliflavus species) was documented when adding 45,000 U/kg xylanase to the diet of laying hens. In conclusion, dietary supplementation of xylanase 45,000 U/kg significantly improved laying hen performance and digestibility. Furthermore, microbiome data suggest that xylanase modulates the laying hen bacterial population beneficially, thus potentially exerting a prebiotic effect.

中文翻译：

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木聚糖酶对性能的影响：蛋鸡的微生物组方法。

家禽饲料中使用的粘性谷物中含有抗营养化合物，例如非淀粉多糖 (NSP)。因此，外源性糖酶通常被添加到单胃饲料中以降解这些 NSP。我们的假设是，木聚糖酶不仅可以提高蛋鸡的性能和消化率，还可以诱导肠道内微生物组成的显着变化，从而可能发挥益生元作用。在这种情况下，需要更好地了解木聚糖酶是否以及如何调节鸡肠道微生物群。为此，本研究评估了日粮中添加木聚糖酶对蛋鸡生产性能、表观全消化道消化率 (ATTD) 和盲肠微生物组的影响。本实验共使用了 96 只 HiSex 蛋鸡（3 种日粮和 2 只母鸡的 16 次重复）。木聚糖酶以 0、45,000（15 g/t XygestTM HT）和 90,000 U/kg（30 g/t Xygest HT）的浓度添加到日粮中。饮食以小麦（~55%）、大豆和向日葵粉为基础。与对照处理相比，最低剂量 45,000 U/kg 显着增加了平均蛋重并提高了饲料效率（P<0.05）。在实验中响应木聚糖酶的添加显着改善了鸡蛋质量参数。例如，在试验的最后 28 天，接受 45,000 U/kg 和 90,000 U/kg 处理的家禽表现出哈夫单位和白蛋白高度的增加（P<0.05）。与对照相比，有机质和粗蛋白的ATTD在45、000 U/kg 治疗组(P<0.05)。此外，与对照组相比，饲喂 90,000 U/kg 组的鸡的总能量和粗脂肪的 ATTD 显着提高。重要的是，16S rRNA 基因分析表明，45,000 U/kg 剂量的木聚糖酶可以改变盲肠微生物组。在蛋鸡日粮中添加 45,000 U/kg 木聚糖酶后，有益细菌（杆菌类；肠球菌科和乳酸杆菌目；默迪巴克菌属、肠球菌属和诺卡氏菌属）显着增加。总之，日粮中添加 45,000 U/kg 的木聚糖酶显着提高了蛋鸡的生产性能和消化率。此外，微生物组数据表明木聚糖酶有益地调节蛋鸡细菌种群，从而可能发挥益生元作用。