Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Fisheries College, Jimei University, Xiamen, 361021, China.
Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Fisheries College, Jimei University, Xiamen, 361021, China.
Fish Shellfish Immunol. 2018 Sep;80:405-415. doi: 10.1016/j.fsi.2018.06.025. Epub 2018 Jun 20.
This study evaluated the effects of supplementing chitooligosaccharide (COS) in low fish meal (FM) diets on growth, immune response, intestine and hepatopancrease histology, and expression of inflammatory and immune-related genes in Pacific white shrimp (Litopenaeus vannamei). A basal diet was formulated using FM and soybean meal (SM) as primary protein sources and considered as a high FM (HFM) diet, then a low FM (LFM) diet was prepared by substituting 50% of FM with SM and supplemented with 0, 0.3, 0.6, 0.9, 1.2 or 1.5 g COS kg diet (LFM, COS3, COS6, COS9, COS12 and COS15 diets). Each diet was fed to quadruplicate groups of shrimp (0.9 g) to apparent satiation three times daily for eight weeks. At the end of the experiment no significant changes in growth and survival rate were observed among treatments (P > 0.05). FM replacement led to significant (P < 0.05) reduction of serum lysozyme activity and significant improvements were obtained by adding 0.3 or 0.6 g kg COS to the LFM diet. A significant decrease in nitric oxide synthase activity was found in LFM group and no beneficial effects could be achieved by COS application. LFM group showed higher hepatopancrease superoxide dismutase and glutathione peroxidase activities than HFM group and further enhancements were obtained by COS application. Hepatopancrease total antioxidant capacity and alkaline phosphatase activity decreased in LFM group and COS supplementation improved their values. Expression of lysozyme, crustin, Pen3 and proPo genes were significantly up-regulated in hepatopancrease of groups received 0.3-0.9 g COS kg diet. FM substitution enhanced the expression of HSP70 and inflammatory genes such as AIF and TNF in hepatopancrease and intestine, and COS administration at a moderate level down-regulated their expression level. Remarkable enhancement in intestinal fold height was obtained by inclusion of 0.3 or 0.6 g COS kg diet compared to the group received LFM diet. Shrimps fed HFM and COS containing diets exhibited higher number of E-cells within their hepatopancrease tubules than the LFM group. The findings in this study clearly demonstrated that COS could enhance non-specific immune response and antioxidant activity, and ameliorate the negative impacts of high SM diets on gut and hepatopancrease health in pacific white shrimp. The optimum inclusion level of COS seems to be 0.3-0.6 g kg of diet.
本研究评估了在低鱼粉（FM）饲料中补充壳寡糖（COS）对南美白对虾（Litopenaeus vannamei）生长、免疫反应、肠道和肝胰腺组织学以及炎症和免疫相关基因表达的影响。使用 FM 和豆粕（SM）作为主要蛋白质来源配制基础饲料，并将其视为高 FM（HFM）饲料，然后用 50%的 FM 替代 SM 并补充 0、0.3、0.6、0.9、1.2 或 1.5 g/kg 饲料的 COS（LFM、COS3、COS6、COS9、COS12 和 COS15 饲料）。将每种饲料分别投喂给 8 周内每天分 3 次投喂至饱食状态的 4 组虾（0.9 g）。实验结束时，处理组之间的生长和成活率没有显著变化（P > 0.05）。FM 替代导致血清溶菌酶活性显著降低（P < 0.05），而在 LFM 饲料中添加 0.3 或 0.6 g/kg COS 则可显著提高其活性。LFM 组一氧化氮合酶活性显著降低，而添加 COS 则无法产生有益效果。LFM 组肝胰腺超氧化物歧化酶和谷胱甘肽过氧化物酶活性高于 HFM 组，添加 COS 可进一步提高其活性。LFM 组肝胰腺总抗氧化能力和碱性磷酸酶活性降低，添加 COS 可改善其值。LFM 组肝胰腺中溶菌酶、壳质素、Pen3 和 proPo 基因的表达显著上调，而添加 0.3-0.9 g/kg COS 可进一步上调其表达。FM 替代增强了 HSP70 和炎症基因（如 AIF 和 TNF）在肝胰腺和肠道中的表达，而中水平添加 COS 则下调了其表达水平。与 LFM 组相比，添加 0.3 或 0.6 g/kg COS 可显著提高肠道褶皱高度。HFM 和含 COS 饲料组虾肝胰腺小管内的 E 细胞数量高于 LFM 组。本研究结果清楚地表明，COS 可以增强非特异性免疫反应和抗氧化活性，并改善高 SM 饲料对南美白对虾肠道和肝胰腺健康的负面影响。COS 的最佳添加水平似乎为 0.3-0.6 g/kg 饲料。
