饲料中添加壳寡糖对花鲈(Lateolabrax japonicus)幼鱼的生长、消化和血清生化指标的影响

本试验旨在研究壳寡糖对花鲈（Lateolabrax japonicus）幼鱼生长，肠道消化，血清生化指标及肠道菌群的影响。本试验选用360尾规格一致的花鲈幼鱼（19.37 g左右）为研究对象。壳寡糖饲料添加浓度设为6组:0%、0.2%、0.4%、0.6%、0.8%、1.0%。设3个平行组，养殖周期45 d。结果显示:（1）生长性能:添加0.6%和0.8%两组的增重率、特定生长率与对照组相比有提高（P>0.05）；（2）肠道消化酶:添加0.6%~1.0%的壳寡糖显著（P<0.05）提高胰蛋白酶活性，0.4%~0.8%的壳寡糖显著（P<0.05）提高了脂肪酶活性；（3）肠道菌群:0.6%~1.0%的壳寡糖显著降低了沙门氏菌数量（P<0.05），大肠杆菌的数量在0.8%时显著降低（P<0.05），双歧杆菌的数量在0.2%~0.6%时显著增加（P<0.05）；（4）血清生化指标:壳寡糖显著提高血清总蛋白和高密度脂蛋白胆固醇含量（P<0.05）；（5）血清非特异性免疫:添加0.6%的壳寡糖显著降低丙二醛（P>0.05），0.2%的壳寡糖增强超氧化物歧化酶、碱性磷酸酶和过氧化物酶活性，添加壳寡糖使溶菌酶的活性显著增强（P<0.05）。研究结果表明:饲料中添加0.6%~0.8%的壳寡糖对花鲈幼鱼生长性能、血脂及肠道健康影响效果最佳。

Effects of dietary Chitosan oligosaccharide on the performance, digestion and serum biochemical indexes of the juvenile Japanese seabass (Lateolabrax japonicus)

This research was conducted to evaluate the effects of dietary supplementation with Chitosan-oligosaccharide (COS) on the growth performance, digestion, serum biochemical indexes and intestinal flora. A total of 360 juvenile Japanese seabass were randomly assigned to six treatment diets that included COS at concentrations of 0%,0.2%,0.4%,0.6%,0.8%,1.0% for 45 d. Each treatment had 3 replicates with 20. The results showed:(1) The growth performance:The weight gain and specific growth rate of Diet3(0.6%) and Diet4(0.8%) were increased compared with the control group (P>0.05); (2) The digestive ferment:The intestinal trypsin activity were significantly increased (P<0.05) in the Diet3(0.6%), Diet4(0.8%) and Diet5(1.0%). Intestinal lipase activity was remarkably increased at Diet2(0.4%),Diet3(0.6%) and Diet4(0.8%) (P<0.05). There was no significant difference in intestinal amylase activity (P>0.05). (3) The serum biochemical indexes:Compared with the control group, the contents of the serum total protein and high-density lipoprotein cholesterol (HDL-C) was obviously increased (P<0.05); (4) The nonspecific immunity:The contents of MDA was decreased significantly (P>0.05) on the Diet3(0.6%). The activities of superoxide dismutase, alkaline phosphatase and peroxidase were all increased (P>0.05) on the Diet1 (0.2%), and the serum lysozyme was significantly increased (P<0.05). (5) Intestinal flora:The number of Salmonella in Diet3 (0.6%), Diet 4(0.8%) and Diet5(1%), and E. coli was significantly decreased (P<0.05) in Diet(0.8%). The quantity of bifidobacteria increased significantly (P<0.05) in Diet1(0.2%), Diet2(0.4%) and Diet3(0.6%). In conclusion, these results indicate that COS can enhance growth and immunity of juvenile Japanese seabass,and the optimum addition level was 0.6%~0.8% in diet.