Barramundi (Lates calcarifer) are a highly valued aquaculture species, and, as obligate carnivores, they have a demonstrated preference for dietary protein over lipid or starch to fuel energetic growth demands. In order to investigate how carnivorous fish regulate nutritional cues, we examined the metabolic effects of feeding two isoenergetic diets that contained different proportions of digestible protein or starch energy. Fish fed a high proportion of dietary starch energy had a higher proportion of liver SFA, but showed no change in plasma glucose levels, and few changes in the expression of genes regulating key hepatic metabolic pathways. Decreased activation of the mammalian target of rapamycin growth signalling cascade was consistent with decreased growth performance values. The fractional synthetic rate (lipogenesis), measured by TAG 2H-enrichment using 2H NMR, was significantly higher in barramundi fed with the starch diet compared with the protein diet (0·6 (se 0·1) v. 0·4 (se 0·1) % per d, respectively). Hepatic TAG-bound glycerol synthetic rates were much higher than other closely related fish such as sea bass, but were not significantly different (starch, 2·8 (se 0·3) v. protein, 3·4 (se 0·3) % per d), highlighting the role of glycerol as a metabolic intermediary and high TAG-FA cycling in barramundi. Overall, dietary starch significantly increased hepatic TAG through increased lipogenesis. Compared with other fish, barramundi possess a unique mechanism to metabolise dietary carbohydrates and this knowledge may define ways to improve performance of advanced formulated feeds.

中文翻译：

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膳食淀粉促进澳洲肺鱼（Lates calcarifer）的肝脏脂肪生成

澳洲肺鱼 (晚期钙化剂) 是一种非常有价值的水产养殖物种，并且作为专性食肉动物，它们对膳食蛋白质的偏好明显高于脂质或淀粉，以满足能量增长的需求。为了研究肉食性鱼类如何调节营养线索，我们研究了喂食两种含有不同比例的可消化蛋白质或淀粉能量的等能量饮食对代谢的影响。饲喂高比例膳食淀粉能量的鱼肝脏 SFA 比例较高，但血浆葡萄糖水平没有变化，调节关键肝脏代谢途径的基因表达几乎没有变化。雷帕霉素生长信号级联的哺乳动物靶标的激活降低与生长性能值降低一致。由 TAG 测量的分数合成速率（脂肪生成）2H-富集使用2与蛋白质饮食相比，食用淀粉饮食的尖吻鲈的 H NMR 显着高于蛋白质饮食（0·6 (瑟0·1)v. 0·4 (瑟0·1) % per d，分别）。肝脏 TAG 结合的甘油合成率远高于其他密切相关的鱼类，如鲈鱼，但没有显着差异（淀粉，2·8（瑟0·3)v. 蛋白质，3·4（瑟0·3) % per d)，突出了甘油在澳洲肺鱼中作为代谢中间体和高 TAG-FA 循环的作用。总体而言，膳食淀粉通过增加脂肪生成显着增加肝脏 TAG。与其他鱼类相比，澳洲肺鱼拥有一种独特的代谢膳食碳水化合物的机制，这种知识可以定义提高高级配方饲料性能的方法。