月桂酸(LA),含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,在抗病和提高免疫生理功能方面发挥着重要作用。本研究的目的是确定日粮月桂酸对生长性能的影响。抗氧化能力,非特异性免疫和肠道微生物学,并评估月桂酸在游泳蟹(Portunustrituberculatus)培养中的环保添加剂的潜力。总共192只初始体重为11.68±0.02g的游泳蟹饲喂6种不同的日粮月桂酸水平,月桂酸的分析值为0.09、0.44、0.80、1.00、1.53、2.91mg/g,分别。每个处理有四个重复,每个重复有8只幼蟹。结果表明,最终重量,体重增加百分比,比增长率,存活率和采食量不受日粮月桂酸水平的显著影响;然而,饲喂0.80和1.00mg/g月桂酸的螃蟹在所有处理中的饲料效率最低。肝胰腺和肌肉中的近似组成不受饮食月桂酸水平的显着影响。饲喂0.80mg/g月桂酸的螃蟹在肝胰腺和肠道中的淀粉酶和脂肪酶活性最高(P<0.05)。饲粮月桂酸水平从0.09mg/g增加到2.91mg/g,肝胰腺和肠道肉碱棕榈酰转移酶(CPT)活性显着降低(P<0.05)。在所有处理中,饲喂0.80和1.00mg/g月桂酸的螃蟹的日粮中观察到最低的葡萄糖和总蛋白浓度以及血淋巴中碱性磷酸酶的活性。饲粮月桂酸从0.09mg/g增加到1.53mg/g,肝胰腺中GSH-Px的活性显着增加。饲粮月桂酸水平对肝胰腺和血淋巴中的MDA没有显着影响。在饲喂1.00mg/g月桂酸的螃蟹中,肝胰腺中cat和gpx的表达最高,然而,与炎症信号通路相关的基因的表达(relive,myd88,traf6,nf-κB)在肝胰腺中上调,膳食月桂酸水平从0.09增加到1.00mg/g,此外,肠道炎症相关基因的表达,饲粮月桂酸水平显著影响机体免疫和抗氧化能力(P<0.05)。饲喂不添加月桂酸的蟹肝胰腺脂质下降面积高于其他饲粮(P<0.05)。与脂质分解代谢相关的基因表达上调,然而,饲喂0.80mg/g月桂酸的螃蟹肝胰腺中与脂质合成相关的基因表达下调。月桂酸改善肝管完整性,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增强肠道屏障功能。此外,日粮1.00mg/g月桂酸显著改善肠道菌群组成,增加了放线菌和红杆菌科的丰度,减少了弧菌的丰度,从而维持肠道微生物群的平衡。相关分析表明,肠道菌群与免疫-抗氧化功能存在一定的相关性。总之,日粮中月桂酸1.00mg/g有利于提高梭子蟹的抗氧化能力和肠道健康。
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.