Nutrition is crucial to grow healthy fish particularly in a context of pollution, overcrowding and pathogen risks. Nowadays, the search for food components able to improve fish health is increasingly developing. Here, the influence of four dietary polyunsaturated fatty acids (PUFAs) that are alpha-linolenic acid (ALA, 18:3n-3), linoleic acid (LA, 18:2n-6), eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) on the sensitivity of rainbow trout (Oncorhynchus mykiss) juveniles to environmentally realistic cadmium (Cd, 0.3 μg/L) concentration was investigated. Fish diets were designed to ensure the specific abundance of one of these individual PUFAs, and were given for a 4-week pre-conditioning period followed by a 6-week Cd exposure period. Focus was put on growth performance and immune responses following a short (24 h) and a long-term (6 weeks) Cd exposure. For each experimental condition, some fish were submitted to a bacterial challenge (24 h) with Aeromonas salmonicida achromogenes at the end of Cd conditioning period. DHA-enriched diet improved growth performances as compared to LA-enriched diet, but also increased ROS production (after short-term exposure to Cd) that could lead to a higher inflammation status, and some immunity-related genes (at short and long-term exposure). We notably highlighted the fact that even a low, environmentally-realistic concentration, Cd can strongly impact the immune system of rainbow trout, and that specific dietary PUFA enrichment strategies can improve growth performance (DHA-enriched diet), provide protection against oxidative stress (ALA- and EPA-enriched diet) and stimulate non-specific immunity.

营养对于养成健康的鱼类至关重要，特别是在污染，人满为患和病原体风险的情况下。如今，寻找能够改善鱼类健康的食品成分的工作正在日益发展。在这里，四种饮食多不饱和脂肪酸（PUFA）的影响是α-亚麻酸（ALA，18：3n-3），亚油酸（LA，18：2n-6），二十碳五烯酸（EPA，20：5n- 3）和二十二碳六烯酸（DHA，22：6n-3）对虹鳟鱼（Oncorhynchus mykiss）的敏感性研究了少年到环境上现实的镉（Cd，0.3μg/ L）的浓度。鱼的饮食设计旨在确保这些个体PUFA中的一种的特定丰度，并给予4周的预处理期，然后进行6周的Cd暴露期。短期（24小时）和长期（6周）Cd暴露后，重点放在生长性能和免疫反应上。对于每种实验条件，将一些鱼用嗜盐气单胞菌产色杆菌进行细菌攻击（24小时）在Cd调节期结束时。与富含LA的饮食相比，富含DHA的饮食改善了生长性能，但也增加了ROS的产生（短期暴露于Cd之后），这可能导致更高的炎症状态，以及一些与免疫有关的基因（无论短期还是长期，期限曝光）。我们特别强调了一个事实，即即使是低的，符合环境要求的浓度，镉也可以强烈影响虹鳟鱼的免疫系统，并且特定的膳食PUFA富集策略可以改善生长性能（富含DHA的饮食），提供抗氧化应激的保护（富含ALA和EPA的饮食）并刺激非特异性免疫。