Laboratory of Fish and Shellfish Nutrition, School of Marine Sciences, Ningbo University, Ningbo, 315211, China.
Laboratory of Fish and Shellfish Nutrition, School of Marine Sciences, Ningbo University, Ningbo, 315211, China.
Fish Shellfish Immunol. 2024 Aug;151:109739. doi: 10.1016/j.fsi.2024.109739. Epub 2024 Jul 2.
Lauric acid (LA), a saturated fatty acid with 12 carbon atoms, is widely regarded as a healthy fatty acid that plays an important role in disease resistance and improving immune physiological function. The objective of this study was to determine the effects of dietary lauric acid on the growth performance, antioxidant capacity, non-specific immunity and intestinal microbiology, and evaluate the potential of lauric acids an environmentally friendly additive in swimming crab (Portunus trituberculatus) culture. A total of 192 swimming crabs with an initial body weight of 11.68 ± 0.02 g were fed six different dietary lauric acid levels, the analytical values of lauric acid were 0.09, 0.44, 0.80, 1.00, 1.53, 2.91 mg/g, respectively. There were four replicates per treatment and 8 juvenile swimming crabs per replicate. The results indicated that final weight, percent weight gain, specific growth rate, survival and feed intake were not significantly affected by dietary lauric acid levels; however, crabs fed diets with 0.80 and 1.00 mg/g lauric acid showed the lowest feed efficiency among all treatments. Proximate composition in hepatopancreas and muscle were not significantly affected by dietary lauric acid levels. The highest activities of amylase and lipase in hepatopancreas and intestine were found at crabs fed diet with 0.80 mg/g lauric acid (P < 0.05), the activity of carnitine palmityl transferase (CPT) in hepatopancreas and intestine significantly decreased with dietary lauric acid levels increasing from 0.09 to 2.91 mg/g (P < 0.05). The lowest concentration of glucose and total protein and the activity of alkaline phosphatase in hemolymph were observed at crabs fed diets with 0.80 and 1.00 mg/g lauric acid among all treatments. The activity of GSH-Px in hepatopancreas significantly increased with dietary lauric acid increasing from 0.09 to 1.53 mg/g, MDA in hepatopancreas and hemolymph was not significantly influenced by dietary lauric acid levels. The highest expression of cat and gpx in hepatopancreas were exhibited in crabs fed diet with 1.00 mg/g lauric acid, however, the expression of genes related to the inflammatory signaling pathway (relish, myd88, traf6, nf-κB) were up-regulated in the hepatopancreas with dietary lauric acid levels increasing from 0.09 to 1.00 mg/g, moreover, the expression of genes related to intestinal inflammatory, immune and antioxidant were significantly affected by dietary lauric acid levels (P < 0.05). Crabs fed diet without lauric acid supplementation exhibited higher lipid drop area in hepatopancreas than those fed the other diets (P < 0.05). The expression of genes related to lipid catabolism was up-regulated, however, and the expression of genes related to lipid synthesis was down-regulated in the hepatopancreas of crabs fed with 0.80 mg/g lauric acid. Lauric acid improved hepatic tubular integrity, and enhanced intestinal barrier function by increasing peritrophic membrane (PM) thickness and upregulating the expression of structural factors (per44, zo-1) and intestinal immunity-related genes. In addition, dietary 1.00 mg/g lauric acid significantly improved the microbiota composition of the intestinal, increased the abundance of Actinobacteria and Rhodobacteraceae, and decreased the abundance of Vibrio, thus maintaining the microbiota balance of the intestine. The correlation analysis showed that there was a relationship between intestinal microbiota and immune-antioxidant function. In conclusion, the dietary 1.00 mg/g lauric acid is beneficial to improve the antioxidant capacity and intestinal health of swimming crab.
月桂酸（LA）是一种具有 12 个碳原子的饱和脂肪酸，被广泛认为是一种健康的脂肪酸，在抗病和改善免疫生理功能方面发挥着重要作用。本研究旨在确定膳食月桂酸对生长性能、抗氧化能力、非特异性免疫和肠道微生物群的影响，并评估月桂酸作为一种环保添加剂在三疣梭子蟹（Portunus trituberculatus）养殖中的潜力。共选用 192 只初始体重为 11.68±0.02 g 的三疣梭子蟹，分别投喂 6 种不同月桂酸水平的饲料，月桂酸的分析值分别为 0.09、0.44、0.80、1.00、1.53 和 2.91 mg/g，每个处理有 4 个重复，每个重复 8 只幼蟹。结果表明，饲料中月桂酸水平对终重、增重率、特定生长率、成活率和饲料效率没有显著影响；然而，投喂 0.80 和 1.00 mg/g 月桂酸饲料的螃蟹的饲料效率最低。肝胰腺和肌肉的粗蛋白组成不受饲料中月桂酸水平的显著影响。肝胰腺和肠道中淀粉酶和脂肪酶的活性在投喂 0.80 mg/g 月桂酸的螃蟹中最高（P<0.05），肝胰腺和肠道中肉碱棕榈酰转移酶（CPT）的活性随着饲料中月桂酸水平从 0.09 增加到 2.91 mg/g 而显著降低（P<0.05）。所有处理中，投喂 0.80 和 1.00 mg/g 月桂酸饲料的螃蟹的血淋巴中葡萄糖和总蛋白浓度最低，碱性磷酸酶活性最高。肝胰腺中 GSH-Px 的活性随着饲料中月桂酸的增加而显著增加，肝胰腺和血淋巴中的 MDA 不受饲料中月桂酸水平的影响。肝胰腺中 cat 和 gpx 的表达在投喂 1.00 mg/g 月桂酸的螃蟹中最高，然而，随着饲料中月桂酸水平从 0.09 增加到 1.00 mg/g，与炎症信号通路相关的基因（relish、myd88、traff6、nf-κB）在肝胰腺中的表达上调，此外，与肠道炎症、免疫和抗氧化相关的基因也受到饲料中月桂酸水平的显著影响（P<0.05）。投喂不含月桂酸补充剂的螃蟹的肝胰腺中脂质滴面积高于投喂其他饲料的螃蟹（P<0.05）。肝胰腺中与脂质分解代谢相关的基因表达上调，而投喂 0.80 mg/g 月桂酸的螃蟹的脂质合成相关基因表达下调。月桂酸通过增加围食膜（PM）厚度和上调结构因子（per44、zo-1）和肠道免疫相关基因的表达来改善肝小管的完整性，增强肠道屏障功能。此外，膳食中 1.00 mg/g 月桂酸显著改善了肠道微生物群落的组成，增加了放线菌和红杆菌科的丰度，降低了弧菌的丰度，从而维持了肠道微生物群落的平衡。相关性分析表明，肠道微生物群与免疫-抗氧化功能之间存在关系。综上所述，膳食中 1.00 mg/g 月桂酸有利于提高三疣梭子蟹的抗氧化能力和肠道健康。
