An 8-week feeding trial was conducted to evaluate the effects of dietary xylanase supplementation on growth performance, digestive enzyme activity, intestinal morphology parameter, intestinal microbiome diversity, and carbohydrate metabolism for juvenile large yellow croaker (Larimichthys crocea). Four levels of xylanase were added to basal diets (0, 600, 1200, and 1800 U kg-1). The results indicated that fish fed the 1200 U kg-1 xylanase diet had higher weight gain than those fed the 0 and 600 U kg-1 xylanase diet. The highest intestinal folds and microvillous height were observed at fish fed the 1200 U kg-1 xylanase diet. High-throughput sequencing revealed that the majority of reads derived from the large yellow croaker digesta belonged to members of Proteobacteria followed by Chloroflex, Bacteroidetes, Spirochaetae, and Firmicute. Supplementation of xylanase in diets increased the relative abundance of Bacteroides and Gemmatimonadete. The higher hepatic glucokinase (GK) and glucose-6-phosphate dehydrogenase (G6PD) activities were observed in fish fed the xylanase supplementation diet. Accordingly, dietary xylanase supplementation upgraded the relative expressions of gk and g6pd genes in liver. In conclusion, optimum dietary xylanase supplementation (600-1200 U kg-1) could improve the growth performance, optimize the intestinal morphology structure and microbiota constitution, and enhance the ability of carbohydrate utilization of juvenile large yellow croaker.

中文翻译：

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膳食中添加外源木聚糖酶对少年大黄鱼（Larimichthys crocea）生长性能，肠道健康和碳水化合物代谢的影响。

进行了为期8周的喂养试验，以评估日粮木聚糖酶对少年大黄鱼（Larimichthys crocea）的生长性能，消化酶活性，肠道形态参数，肠道微生物组多样性和碳水化合物代谢的影响。将四种水平的木聚糖酶添加到基础饮食中（0、600、1200和1800 U kg-1）。结果表明，饲喂1200 U kg-1木聚糖酶日粮的鱼增重高于饲喂0和600 U kg-1木聚糖酶日粮的鱼。在饲喂1200 U kg-1木聚糖酶日粮的鱼中，观察到最高的肠皱褶和微绒毛高度。高通量测序表明，大黄鱼消化物中的大多数读物属于变形杆菌属，其次为Chloroflex，拟杆菌，Spirochaetae和Firmicute。饮食中添加木聚糖酶可增加拟杆菌和Gemmatimonadete的相对丰度。在补充木聚糖酶饮食的鱼中观察到较高的肝葡萄糖激酶（GK）和6-磷酸葡萄糖脱氢酶（G6PD）活性。因此，膳食木聚糖酶的补充提高了肝脏中gk和g6pd基因的相对表达。总之，最佳膳食木聚糖酶（600-1200 U kg-1）可以改善生长性能，优化肠道形态结构和微生物群组成，并增强少年大黄鱼的碳水化合物利用能力。在补充木聚糖酶饮食的鱼中观察到较高的肝葡萄糖激酶（GK）和6-磷酸葡萄糖脱氢酶（G6PD）活性。因此，膳食木聚糖酶的补充提高了肝脏中gk和g6pd基因的相对表达。总之，最佳膳食木聚糖酶（600-1200 U kg-1）可以改善生长性能，优化肠道形态结构和微生物群组成，并增强少年大黄鱼的碳水化合物利用能力。在补充木聚糖酶饮食的鱼中观察到较高的肝葡萄糖激酶（GK）和6-磷酸葡萄糖脱氢酶（G6PD）活性。因此，膳食木聚糖酶的补充提高了肝脏中gk和g6pd基因的相对表达。总之，最佳日粮木聚糖酶（600-1200 U kg-1）可以提高生长性能，优化肠道形态结构和微生物群组成，并增强少年大黄鱼的碳水化合物利用能力。