College of Fisheries, Hubei Provincial Engineering Laboratory for Pond Aquaculture, National Demonstration Center for Experimental Aquaculture Education, Huazhong Agricultural University, Wuhan 430070, China.
Institute of Parasitology, McGill University, Saint-Anne-de-Bellevue, QC H9X 3V9, Canada.
Gigascience. 2018 Oct 1;7(10):giy111. doi: 10.1093/gigascience/giy111.
The ultrahigh density intensive farming model of grass carp (Ctenopharyngodon idellus) may elicit growth inhibition, decrease flesh quality, and increase disease susceptibility of fish. The degradation in quality and excessive fat accumulation in cultured C. idellus have long been attributed to possible alterations in the lipid metabolism of fish muscle tissues as a result of overnutrition from artificial diets. To investigate the effects of different diets on fish muscle quality, a large-scale metabolomics study was performed on 250 tails of C. idellus.
The experimental fish were divided into four groups based on sex and diet-female artificial feed (FAF), female grass feed, male artificial feed (MAF), and male grass feed (MGF). After a 113-day rearing period, the artificial feed (AF) group showed a significantly higher total mass of muscle fat (P < 0.01), with the FAF group being the highest. Metabolomics profiling based on liquid chromatography-mass spectrometry revealed distinctive patterns of clustering according to the four groups. Overall, artificial feeding was associated with higher concentrations of docosapentaenoic acid, dihomo-gamma-linolenic acid, and arachidonic acid, whereas grass feeding was associated with elevated n-3 unsaturated fatty acids (UFAs) such as eicosapentaenoic acid, alpha-linolenic acid, and gamma-linolenic acid. Artificial feeding also resulted in significant increased docosahexaenoic acid in MAF muscle than in MGF fish, whereas there was no significance in the comparison of female samples. Metabolic pathway analyses using both targeted and untargeted approaches consistently revealed that arachidonic acid metabolism and steroid hormone biosynthesis pathways were significantly different between AF and grass fed groups.
Our results suggest that grass is a better source of dietary fatty acid and protein when compared to artificial feed. Grass feeding could effectively lower triglycerides in serum, reduce fat accumulation, and alter lipid compositions in fish muscle by increasing the concentrations of n-3 UFAs, leading to better nutrition and health.
草鱼（Ctenopharyngodon idellus）的超高密度集约化养殖模式可能会引起鱼类生长抑制、肉质下降和疾病易感性增加。长期以来，养殖草鱼的质量下降和过度脂肪积累归因于人工饲料过度营养导致鱼类肌肉组织脂质代谢可能发生变化。为了研究不同饲料对鱼类肌肉品质的影响，对 250 尾草鱼进行了大规模代谢组学研究。
根据性别和饲料将实验鱼分为四组-雌性人工饲料（FAF）、雌性草饲料、雄性人工饲料（MAF）和雄性草饲料（MGF）。经过 113 天的饲养期后，人工饲料（AF）组肌肉脂肪总量明显较高（P<0.01），其中 FAF 组最高。基于液相色谱-质谱的代谢组学分析显示，根据四组的聚类模式存在明显差异。总的来说，人工喂养与二十二碳五烯酸、二高-γ-亚麻酸和花生四烯酸的浓度升高有关，而草食与二十碳五烯酸、α-亚麻酸和γ-亚麻酸等 n-3 不饱和脂肪酸（UFA）的浓度升高有关。人工喂养还导致 MAF 肌肉中的二十二碳六烯酸明显高于 MGF 鱼类，而雌性样本之间没有差异。使用靶向和非靶向方法的代谢途径分析一致表明，在 AF 和草食组之间，花生四烯酸代谢和甾体激素生物合成途径存在显著差异。
与人工饲料相比，草是更好的饮食脂肪酸和蛋白质来源。草食可以通过增加 n-3 UFA 的浓度有效地降低血清中的甘油三酯，减少脂肪积累，并改变鱼类肌肉中的脂质组成，从而获得更好的营养和健康。
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