A 12-week feeding trial was performed to determine the dietary copper (Cu) requirement of postlarval coho salmon (Oncorhynchus kisutch). The postlarvae were reared on six experimental diets containing either 0.4, 1.9, 3.8, 5.6, 7.6 or 9.1 mg Cu/kg, provided as copper sulphate pentahydrate (CuSO₄·5H₂O). The highest specific growth rate (SGR) and condition factor (CF) were observed in fish fed with 5.6 mg Cu/kg diet, which was significantly higher (p < .05) than the 0.4 mg Cu/kg treatment. Feed conversion ratio (FCR) showed an inverse trend with SGR. Whole-body lipid was significantly increased (p < .05) with dietary Cu concentration up to 5.6 mg/kg and decreased thereafter. Fish fed with 9.1 mg Cu/kg diet exhibited the highest Cu concentrations in vertebrae and whole body. The total hepatic superoxide dismutase (T-SOD) and catalase (CAT) activities were positively affected by the dietary Cu concentration up to 5.6 and 7.6 mg/kg respectively. The lowest hepatic malondialdehyde (MDA) content was found in 5.6 mg/kg treatment. Hepatic lipoprotein lipase (LPL) and hepatic lipase (HL) contents significantly decreased (p < .05) with increasing Cu level up to 5.6 mg/kg and then levelled off. Analyses based on the SGR, Cu concentrations in whole body and vertebrae, the optimal dietary Cu requirements for postlarval coho salmon were estimated to be 5.1, 5.5 and 5.2 mg/kg respectively.

中文翻译：

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银鲑幼体 (Oncorhynchus kisutch) 的膳食铜需求量

进行了为期 12 周的喂养试验，以确定银鲑幼体 ( Oncorhynchus kisutch ) 的日粮铜 (Cu) 需求量。用六种含有 0.4、1.9、3.8、5.6、7.6 或 9.1 mg Cu/kg 的试验日粮饲养后期幼体，以硫酸铜五水合物 (CuSO ₄ ·5H ₂ O) 的形式提供。在饲喂 5.6 mg Cu/kg 日粮的鱼中观察到最高的比生长率 (SGR) 和条件因子 (CF)，显着高于 0.4 mg Cu/kg 处理的鱼 ( p < .05)。饲料转化率（FCR）与 SGR 呈相反趋势。全身血脂明显升高（p < .05) 日粮铜浓度高达 5.6 mg/kg 并随后下降。饲喂 9.1 mg Cu/kg 日粮的鱼在椎骨和全身中的 Cu 浓度最高。总肝超氧化物歧化酶 (T-SOD) 和过氧化氢酶 (CAT) 活性受到膳食铜浓度分别高达 5.6 和 7.6 mg/kg 的积极影响。在 5.6 mg/kg 处理中发现最低的肝丙二醛 (MDA) 含量。肝脂蛋白脂肪酶 (LPL) 和肝脂肪酶 (HL) 含量随着铜含量增加至 5.6 mg/kg 显着下降 ( p  < .05)，然后趋于平稳。基于 SGR、全身和椎骨中铜浓度的分析，后期银鲑的最佳日粮铜需求量估计分别为 5.1、5.5 和 5.2 mg/kg。