Carnivorous common snook (Centropomus undecimalis) has potential for aquaculture, but its protein requirement in diet is 500 g kg⁻¹ and the energetic role of lipids in this species has not been explored. Thus, this study investigated the ability of juvenile common snook (8.7 ± 1.2 g) to use dietary lipids as an energy source. The fish were fed four practical diets with two protein levels (400 and 500 g kg⁻¹) associated with two lipid levels (60 and 120 g kg⁻¹) for 12 weeks. Growth performance significantly improved with increasing dietary lipid levels, but no significant difference was observed at the protein level. Fish fed the 400:60 (protein: lipid level) diet exhibited significantly higher feed conversion ratios than those fed 400:120, 500:60 and 500:120 diets, but fish fed the 400:120 diet had significantly higher protein efficiency ratios. Juvenile common snook showed the ability to modulate digestive protease and lipase secretion when dietary protein or lipid levels were modified. The activity of alanine aminotransferase decreased as the dietary lipid level increased (p < .05), while fructose-1 and 6-bisphosphatase activities were not significantly affected by dietary protein or lipid levels. Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and pyruvate kinase activities increased as dietary protein and lipid levels increased (p < .05). The results of this study indicate that an increase in dietary lipid level has a protein-sparing effect and that the diet containing 400 g kg⁻¹ protein with 120 g kg⁻¹ lipid is suitable for growth and effective protein utilization in common snook.

中文翻译：

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饮食脂类对普通斯诺克 Centropomus undecimalis (Bloch, 1792) 幼鱼的生理和代谢蛋白质节约效应

肉食性普通斯诺克（Centropomus undecimalis）具有水产养殖潜力，但其饮食中的蛋白质需求量为500 g kg ^-1并且尚未探索脂质在该物种中的能量作用。因此，本研究调查了幼鱼 (8.7 ± 1.2 g) 使用膳食脂质作为能量来源的能力。给鱼喂食四种实际饮食，两种蛋白质水平（400 和 500 g kg ^-1）与两种脂质水平（60 和 120 g kg ^-1) 12 周。随着日粮脂质水平的增加，生长性能显着提高，但在蛋白质水平上没有观察到显着差异。饲喂 400:60（蛋白质：脂质水平）日粮的鱼表现出明显高于饲喂 400:120、500:60 和 500:120 日粮的饲料转化率，但饲喂 400:120 日粮的鱼的蛋白质效率比明显更高。当日粮蛋白质或脂质水平被改变时，幼鱼表现出调节消化蛋白酶和脂肪酶分泌的能力。丙氨酸氨基转移酶的活性随着日粮脂质水平的增加而降低（p < .05)，而果糖 1 和 6-双磷酸酶活性不受膳食蛋白质或脂质水平的显着影响。6-磷酸葡萄糖脱氢酶、6-磷酸葡萄糖酸脱氢酶和丙酮酸激酶活性随着日粮蛋白质和脂质水平的增加而增加（p  < .05）。本研究结果表明，日粮脂质水平的增加具有节约蛋白质的作用，含有400 g kg ^-1蛋白质和120 g kg ^-1脂质的日粮适合普通斯诺克的生长和有效蛋白质利用。