A feeding experiment was conducted to determine the optimum selenium requirement in juvenile Nile tilapia. Each of six purified diets with Se‐methionine levels at 0.05, 0.21, 0.41, 0.57, 0.79 and 1.00 mg/kg was assayed in triplicate with initial body weight of 3.00 ± 0.01 g for 8 weeks. The growth of fish was obviously increased when the dietary Se was less than 0.57 mg/kg diet and reached a plateau when the dietary Se was ≥0.57 mg/kg. Serum and hepatopancreatic glutathione peroxidase (GPx) activity increased markedly when the dietary Se was less than 0.57 mg/kg, but then decreased when the dietary Se was higher than 0.57 mg/kg. The malondialdehyde contents in hepatopancreas were significantly decreased when the dietary Se was higher than 0.79 mg/kg. No significant differences were observed in hepatopancreatic total antioxidant capability (T‐AOC) among the groups (p > .05). The results of this study indicated that Se addition as Se‐methionine was essential, while both the deficiency and excess levels of dietary Se would cause negative effects on growth or antioxidant capability in juvenile Nile tilapia. Based on broken‐line regression of WG and piecewise regression of liver GPx, the optimum requirement of Se for juvenile Nile tilapia is 0.57 mg/kg diet.

中文翻译：

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尼罗罗非鱼幼鱼的最佳硒需求量

进行了饲养试验以确定幼年尼罗罗非鱼的最佳硒需求量。六种精制饲料中的每一种，其硒蛋氨酸水平分别为 0.05、0.21、0.41、0.57、0.79 和 1.00 mg/kg，初始体重为 3.00 ± 0.01 g，持续 8 周，一式三份。当日粮硒小于0.57mg/kg日粮时，鱼的生长明显增加，当日粮硒≥0.57mg/kg时达到平台期。血清和肝胰腺谷胱甘肽过氧化物酶 (GPx) 活性在膳食硒低于 0.57 mg/kg 时显着增加，但在膳食硒高于 0.57 mg/kg 时下降。当日粮硒高于0.79 mg/kg时，肝胰腺中丙二醛含量显着降低。各组之间的肝胰腺总抗氧化能力（T-AOC）没有显着差异（p > .05）。本研究结果表明，硒作为硒蛋氨酸添加是必不可少的，而日粮硒的缺乏和过量都会对尼罗罗非鱼幼鱼的生长或抗氧化能力产生负面影响。基于 WG 的折线回归和肝脏 GPx 的分段回归，尼罗罗非鱼幼鱼对硒的最佳需求量为 0.57 mg/kg 日粮。