This study evaluated the effect of black soldier fly (Hermetia illucens) larvae oil (BO) produced by a novel technique, subcritical butane extraction, on the flesh quality, lipid nutrients and muscle growth of rainbow trout (Oncorhynchus mykiss) fillet, and investigated the alleviating mechanisms of dietary astaxanthin (AST) supplementation. Two hundred and forty fish (215.16 ± 2.30 g) were distributed to three groups with four replicates. Fish were fed three experimental diets for 8 weeks: the control diet (CD diet), total fish oil of the CD diet was replaced with BO to formulate the BO100 diet, and then 1 g/kg AST was supplemented with the BO100 diet to formulate the AST diet. Results showed that the final body weight and the sarcomere length of fillet were significantly increased and the protein phosphorylation levels of mammalian target of rapamycin (mTOR) and p70 S6 kinase were enhanced in the BO100 group compared to the CD group (P < 0.05). However, there was a reduction in the hardness, springiness and chewiness of fillets, with a decrease in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in the fish of the BO100 group (P < 0.05). Supplementation of AST in the BO100 diet mitigated the impairment of springiness and chewiness and further promoted the sarcomere length of fillet (P < 0.05). Furthermore, dietary AST partially restored the EPA and DHA content of fillet by increasing the phosphorylation levels of serine/threonine kinase (AKT) and AMP-activated protein kinase α (AMPKα) (P < 0.05) and activating the gene expression of unsaturated fatty acid synthesis. To conclude, BO produced by subcritical butane extraction can be a readily available oil source for rainbow trout feed that can be used to promote muscle growth in rainbow trout. Further dietary AST supplementation can alleviate BO-induced lipid accumulation, restore DHA levels and improve the flesh quality of rainbow trout fillet.

中文翻译：

---

膳食虾青素通过哺乳动物雷帕霉素靶点和 AMP 活化蛋白激酶途径减轻黑水虻油诱导的 Oncorhynchus mykiss 脂肪酸含量和肌肉质量的负变化


本研究评价了亚临界丁烷提取新技术生产的黑水虻 （Hermetia illucens） 幼虫油 （BO） 对虹鳟鱼 （Oncorhynchus mykiss） 鱼片肉质、脂质营养和肌肉生长的影响，并探讨了膳食虾青素 （AST） 补充剂的缓解机制。将 240 条鱼 （215.16 ± 2.30 g） 分为三组，每组 4 次重复。鱼饲喂 3 种实验日粮，持续 8 周：对照日粮（CD 日粮），用 BO 代替 CD 日粮的总鱼油配制 BO100 日粮，然后补充 1 g/kg AST 和 BO100 日粮配制 AST 日粮。结果显示，与 CD 组相比，BO100 组大鼠最终体重和鱼片肌节长度显著增加，哺乳动物雷帕霉素靶蛋白 （mTOR） 和 p70 S6 激酶的蛋白磷酸化水平增强 （P < 0.05）。然而，鱼片的硬度、弹性和咀嚼性降低，BO100组鱼的二十碳五烯酸 （EPA） 和二十二碳六烯酸 （DHA） 水平降低 （P < 0.05）。在 BO100 日粮中添加 AST 减轻了弹性和咀嚼感的损害，并进一步促进了鱼片的肌节长度 （P < 0.05）。此外，日粮 AST 通过增加丝氨酸/苏氨酸激酶 （AKT） 和 AMP 活化蛋白激酶 α （AMPKα） 的磷酸化水平和激活不饱和脂肪酸合成基因表达，部分恢复了鱼片的 EPA 和 DHA 含量 （P < 0.05）。总而言之，亚临界丁烷提取产生的 BO 可以成为虹鳟鱼饲料的现成油源，可用于促进虹鳟鱼的肌肉生长。 进一步补充 AST 可以减轻 BO 诱导的脂质积累，恢复 DHA 水平并改善虹鳟鱼片的肉质。