中文摘要：

本试验旨在研究变温条件下不同投喂水平对施氏鲟幼鱼消化酶、代谢酶和抗氧化酶活性的影响。试验水温设恒温[（22.0±0.1）℃]和变温[（22±2）℃]2种模式,并根据投喂水平分为6组,分别为恒温100%饱食组（HW-100组）、变温100%饱食组（BW-100组）、变温90%饱食组（BW-90组）、变温80%饱食组（BW-80组）、变温70%饱食组（BW-70组）、变温60%饱食组（BW-60组）。将平均体重为（34.9±0.8）g的施氏鲟幼鱼随机分为6组,每组4个重复,每个重复15尾鱼,养殖周期为42 d。结果表明：变温条件下,在60%-80%范围内,随着投喂水平的降低,胃及瓣肠蛋白酶活性均显著升高（P〈0.05）。与HW-100组相比,BW-60组与BW-70组的胃和瓣肠蛋白酶活性均显著升高（P〈0.05）。变温条件下,十二指肠和瓣肠淀粉酶活性及瓣肠脂肪酶活性均随投喂水平的降低呈先升高后下降的趋势。BW-80组十二指肠淀粉酶活性显著高于HW-100组及BW-100组（P〈0.05）,BW-80组和BW-90组瓣肠淀粉酶活性显著高于其他各组（P〈0.05）。所有变温投喂组瓣肠脂肪酶活性均显著低于HW-100组（P〈0.05）。除BW-70组外,各变温投喂组血清丙氨酸转氨酶（ALT）活性均显著高于HW-100组（P〈0.05）。与HW-100组相比,BW-60组、BW-70组血清超氧化物歧化酶（SOD）活性显著降低（P〈0.05）。在变温条件下,在60%-90%范围内,鱼体血清总抗氧化能力（T-AOC）和黄嘌呤氧化酶（XOD）活性均随着投喂水平的降低整体呈先下降后上升的趋势,且均在投喂水平为80%时降至最低值。与HW-100组相比,BW-60组、BW-70组及BW-100组血清T-AOC显著升高（P〈0.05）,且BW-60组和BW-90组血清XOD活性显著升高（P〈0.05）。综上所述,在周期性变温条件下,施氏鲟幼鱼可通过提高蛋白酶活性,即提高对饲料蛋白质消化效率的方式来补偿其对饲料蛋白质摄入的不足。与恒温100%饱食相比,变温条件下各投喂

英文摘要：

The aim of this study was to investigate the effects of different ration levels in temperature fluctuation on digestive enzyme,metabolic enzyme and antioxidase activities of juvenile Amur sturgeon（ Acipenser schrenckii Brandt）. Two water temperatures were designed,one was constant temperature [（ 22. 0 ± 0. 1） ℃]and another was variable temperature [（ 22 ± 2） ℃]. Six groups according to different ration levels were arranged,and they were constant temperature 100% satiation group（ HW-100 group）,variable temperature100% satiation group（ BW-100 group）,variable temperature 90% satiation group（ BW-90 group）,variable temperature 80% satiation group（ BW-80 group）,variable temperature 70% satiation group（ BW-70 group）and variable temperature 60% satiation group（ BW-60 group）. Juvenile Amur sturgeon with the average body weight of（ 34.9 ± 0.8） g were randomly divided into 6 groups with 4 replicates per group and 15 fish per replicate. The experiment lasted for 42 days. The results showed as follows： under the condition of temperature fluctuation,during 60% to 80 % of ration levels,the protease activity of stomach and valvula intestine was significantly increased with ration level decreasing（ P〈 0.05）. The protease activity of stomach and valvula intestine in BW-60 group and BW-70 group was significantly higher than that in HW-100 group（ P〈 0.05）. Under the condition of temperature fluctuation,the amylase activity of duodenum and valvula intestine and the lipase activity of valvula intestine were firstly increased and then declined with ration level decreasing. The amylase activity of duodenum in BW-80 group was significantly higher than that in HW-100 group and BW-100 group（ P〈0.05）,and the amylase activity of valvula intestine in BW-80 group and BW-90 group was significantly higher than that in other groups（ P 〈 0. 05）. The lipase activity of valvula intestine in all variable temperature groups was significantly lower than that in HW-100 group（ P?