Li Zhao, Dong Kang, Xu Yuling, Wang Yaxin, Hou Zhishuai, Gao Qinfeng, Dong Shuanglin
Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, Shandong, China.
Fisheries College, Ocean University of China, Qingdao, 266001, Shandong, China.
Fish Physiol Biochem. 2025 Sep 13;51(5):164. doi: 10.1007/s10695-025-01555-2.
Rainbow trout (Oncorhynchus mykiss), which is rich in high-quality protein and polyunsaturated fatty acids (PUFAs), is one of the most commercially important aquaculture species worldwide. The fatty acid profiles of trout, however, might be substantially influenced by different stocking densities. The present study aims to evaluate the effects of stocking density on the fatty acid composition and hepatic metabolomics of rainbow trout. Juvenile rainbow trout were reared for 84 days in circular tanks at 3 distinct levels of stocking density, i.e., low (group LD, 9.15 g/L), moderate (group MD, 13.65 g/L), and high (group HD, 27.31 g/L). The results showed that the levels of C22:6 n-3 (Docosahexaenoic acid, DHA) and total n-3 PUFAs in the dorsal muscles of the fish at group MD were significantly higher than those at groups LD and HD (p < 0.05). For ventral muscles, fish at group HD showed significantly decreased content of C16:1n-9 (palmitoleic acid) and n-3 PUFAs compared to those at groups LD and MD (p < 0.05). Hepatic fatty acid profiles showed significant reductions in monounsaturated fatty acids (MUFAs) for the fish at groups MD and HD compared to those at group LD (p < 0.05). Moreover, the concentrations of total n-6 PUFAs in the dorsal muscle were positively correlated with stocking density (R = 0.7357, p = 0.0238), while the levels of total n-3 PUFAs in the ventral muscle (R = - 0.8478, p = 0.0039) and the levels of total MUFAs in the liver (R = - 0.7837, p = 0.0101) showed negative correlations to the fish stocking densities. Metabolomics analyses further revealed that stocking density influenced the pathways related to glycerophospholipid metabolism, fatty acid degradation, and arachidonic acid metabolism. The results suggested that high stocking density altered fatty acid profiles and enhanced antioxidant and inflammatory responses in rainbow trout, providing valuable insights for optimizing aquaculture practices to improve the nutritional quality of farmed trout.
虹鳟（Oncorhynchus mykiss）富含优质蛋白质和多不饱和脂肪酸（PUFAs），是全球商业上最重要的水产养殖品种之一。然而，鳟鱼的脂肪酸组成可能会受到不同放养密度的显著影响。本研究旨在评估放养密度对虹鳟脂肪酸组成和肝脏代谢组学的影响。将虹鳟幼鱼在圆形水箱中以3种不同的放养密度水平饲养84天，即低密度（LD组，9.15 g/L）、中度密度（MD组，13.65 g/L）和高密度（HD组，27.31 g/L）。结果表明，MD组鱼背肌中C22:6 n-3（二十二碳六烯酸，DHA）和总n-3 PUFAs水平显著高于LD组和HD组（p < 0.05）。对于腹侧肌肉，与LD组和MD组相比，HD组鱼的C16:1n-9（棕榈油酸）和n-3 PUFAs含量显著降低（p < 0.05）。肝脏脂肪酸组成显示，与LD组相比，MD组和HD组鱼的单不饱和脂肪酸（MUFAs）显著减少（p < 0.05）。此外，背肌中总n-6 PUFAs浓度与放养密度呈正相关（R = 0.7357，p = 0.0238），而腹侧肌肉中总n-3 PUFAs水平（R = -0.8478，p = 0.0039）和肝脏中总MUFAs水平（R = -0.7837，p = 0.0101）与鱼的放养密度呈负相关。代谢组学分析进一步表明，放养密度影响了与甘油磷脂代谢、脂肪酸降解和花生四烯酸代谢相关的途径。结果表明，高放养密度改变了虹鳟的脂肪酸组成，增强了其抗氧化和炎症反应，为优化水产养殖实践以提高养殖鳟鱼的营养质量提供了有价值的见解。
