Juvenile brook trout were fed on six isonitrogenous and isolipidic diets, containing graded levels of gelatinized corn starch (50, 100, 150, 200, 250, 300 g/kg diet) for 81 days. Cellulose was used to compensate carbohydrate loss. The weight gain, specific growth rate and protein efficiency ratio increased as the dietary carbohydrate level increased from 50 to 150 g/kg, but decreased thereafter (p < .05). Quadratic regression analysis revealed that the optimum dietary carbohydrate level was in the range of 187.1–194.1 g/kg. In addition, serum alanine transaminase and aspartate transaminase activities, as well as glucose content, were highest in the group fed on 300 g/kg carbohydrate (p < .05). The hepatic malondialdehyde level increased with dietary carbohydrate levels (p < .05). The hepatic lysozyme activity increased as dietary carbohydrate level increased from 50 to 150 g/kg and decreased thereafter (p < .05). The overall survival rate after hypoxia challenge (45 min; dissolved oxygen content: 2.2 mg L⁻¹) decreased with dietary carbohydrate levels (p < .05). Taken together, these results suggested that optimal level of dietary carbohydrate could improve growth performance. However, excessive dietary carbohydrate intake (> 250 g/kg) may decrease innate immunity status, increase oxidative stress and reduce resistance to hypoxia stress in brook trout.

中文翻译：

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日粮碳水化合物水平对font鳟的生长性能，先天免疫，抗氧化能力和耐缺氧性的影响

幼溪鳟鱼以六种等氮和等脂日粮喂养，这些日粮含有分级水平的糊化玉米淀粉（日粮为50、100、150、200、250、300 g / kg），持续81天。纤维素用于补偿碳水化合物的损失。随着日粮碳水化合物水平从50 g / kg增加到150 g / kg，体重增加，比生长速率和蛋白质效率比增加，但此后降低（p  <.05）。二次回归分析显示，最佳饮食碳水化合物水平在187.1–194.1 g / kg的范围内。此外，饲喂300 g / kg碳水化合物的组的血清丙氨酸转氨酶和天冬氨酸转氨酶活性以及葡萄糖含量最高（p  <.05）。肝丙二醛水平随饮食中碳水化合物水平的升高而增加（p <.05）。肝溶菌酶活性随着饮食中碳水化合物水平从50 g / kg增加到150 g / kg而增加（p  <.05）。缺氧挑战后的总生存率（45分钟；溶解氧含量：2.2 mg L ^-1）随着饮食中碳水化合物水平的降低而降低（p  <.05）。综上所述，这些结果表明饮食中碳水化合物的最佳水平可以改善生长性能。但是，饮食中碳水化合物的摄入过多（> 250 g / kg）可能会降低河鳟的先天免疫状态，增加氧化应激并降低对低氧胁迫的抵抗力。