A finishing diet strategy is effective at increasing fillet long‐chain n‐3 fatty acid content in fish consuming sustainable plant oil‐based diets. This study investigates the outcomes of a fish oil finishing diet upon the hepatic fatty acid and transcriptome profile in rainbow trout (Oncorhynchus mykiss). Fish were placed on one of three feeding treatments: (1) FO: a fish oil (FO) diet for 20 weeks, (2) VO/FO: a vegetable oil (VO) diet during weeks 1–12 then the FO diet for 8 weeks, or (3) VO/fd/FO: the VO diet between weeks 1–12, 2 weeks of feed deprivation, then the FO diet for 6 weeks. Hepatic fatty acid and transcriptome profiles were analyzed at week 12, 14, and 20. Hepatic fatty acid profiles at week 12 were similar to dietary profiles; transcriptomic analyses indicated 131 differentially regulated genes (DEG) between VO‐ and FO‐fed fish, characterized by VO‐induced up‐regulation of cholesterol and long‐chain fatty acyl‐CoA synthesis and oxidation–reduction processes. At week 14, the hepatic fatty acid profile was similar between VO/FO and FO, although concentrations of 18:3n‐3 remained higher in the VO/FO group. Thirty‐three DEG were detected at week 14 with enrichment of genes associated with extracellular matrix assembly, supporting liver remodeling during the early finishing diet period. Only five DEG were detected at week 20 between VO/FO and FO. Collectively, these findings suggest that it takes several weeks for liver to reach a homeostatic state, even after the hepatic fatty acid equilibration following a finishing diet.

中文翻译：

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虹鳟鱼（Oncorhynchus mykiss）从以植物油为基础的饮食过渡到以鱼油为基础的饮食期间的肝脂肪酸和转录组特征

精加工日粮策略可有效增加食用可持续植物油基日粮的鱼的鱼片长链 n-3 脂肪酸含量。本研究调查了鱼油精加工日粮对虹鳟鱼 ( Oncorhynchus mykiss )肝脏脂肪酸和转录组谱的影响）。将鱼置于三种喂养处理中的一种：(1) FO：鱼油 (FO) 饮食 20 周，(2) VO/FO：第 1-12 周的植物油 (VO) 饮食，然后 FO 饮食8 周，或 (3) VO/fd/FO：第 1-12 周之间的 VO 饮食，2 周的饲料剥夺，然后是 6 周的 FO 饮食。在第 12、14 和 20 周分析了肝脂肪酸和转录组谱。第 12 周的肝脂肪酸谱与饮食谱相似；转录组学分析表明，VO 和 FO 喂养的鱼之间有 131 个差异调节基因（DEG），其特征是 VO 诱导的胆固醇和长链脂肪酰基辅酶 A 合成和氧化还原过程的上调。在第 14 周，VO/FO 和 FO 之间的肝脏脂肪酸谱相似，尽管 VO/FO 组中 18:3n-3 的浓度仍然较高。在第 14 周检测到 33 个 DEG，富含与细胞外基质组装相关的基因，支持早期完成饮食期间的肝脏重塑。在第 20 周 VO/FO 和 FO 之间仅检测到 5 个 DEG。总的来说，这些发现表明肝脏需要数周才能达到稳态，即使在完成饮食后肝脏脂肪酸平衡之后也是如此。