饥饿与再投喂对黑鲷幼鱼体质量变化、生化组成及肝脏消化酶活性的影响

Effects of starvation and re-feeding on body weight,tissue biochemical composition and hepatic digestive enzyme activity in juvenile black seabream,Acanthopagrus schlegeli

在室内水温23-26℃的条件下,分别对黑鲷（Acanthopagrus schlegeli）幼鱼进行不同时间的饥饿（0d、3d、5d、10d、15d、20d）处理和饥饿20d后的恢复投喂（3d、5d、10d、15d）实验,每个处理组各设3个重复,分别测定其体质量、肥满度、肝体指数、肌肉与血清主要生化组成以及肝脏消化酶活性的变化。结果表明：1）在饥饿过程中,黑鲷幼鱼体质量、肥满度、肝体指数均显著性下降（P〈0.05）;恢复投喂后,三者均有不同程度的恢复。2）肌肉脂肪含量在饥饿3d时即表现出下降趋势,但在随后的饥饿时间里,肌肉脂肪含量的下降趋势并不明显（P〉0.05）,而肌肉蛋白含量在饥饿5d以内也无明显的变化,至10d时才出现显著性的降低。但随着饥饿时间的延长,肌肉蛋白含量均显著降低（P〈0.05）。恢复投喂第10天时,肌肉中的各项生化指标基本恢复至饥饿前水平。由此推测,饥饿胁迫下黑鲷是先动用了体组织的脂肪,而后再利用蛋白质且主要靠消耗蛋白质来满足维持生命活动所需的能量。3）血清中总蛋白、血糖、甘油三酯、胆固醇在饥饿阶段显著下降（P〈0.05）,恢复投喂第5天时,各指标均已基本回升到饥饿前水平。相比之下,血糖水平的恢复较快,随后逐渐趋于平稳。4）肝脏中类胰蛋白酶和脂肪酶的活性在饥饿阶段呈上升趋势,恢复投喂后则有所下降。淀粉酶活力在饥饿过程中呈下降趋势,恢复投喂后有所回升,但在整个实验期间淀粉酶活性并无显著性的变化（P〉0.05）。

Because of high variation of food availability in natural aquatic systems, fish may experience different degrees of starvation during their growth, especially overwinter period which may lead to variation in body weight, main biochemical composition of carcass and digestive enzyme activities in fish. The present experiment was designed to study the effects of starvation and subsequent re-feeding on body weight, main biochemical composition of muscle and serum, hepatic digestive enzyme activity in juvenile black seabream （Acanthopagrus schlegeli） cultured in indoor aquarium at water temperature 23-26℃. The fish were divided into six groups, of which three groups were prepared for sampling during a different periods of starvation （0 d, 3 d, 5 d, 10 d, 15 d and 20 d）, and the others were prepared for sampling during a different period of re-feeding （3 d, 5d, 10d, 15 d） after 20 d starvation. Each treatment was assigned to triplicate aquariums. The results were as follows： 1） body weight, condition factor, hepatosomatic index increased significantly during the starvation and all those were significantly differenct from those of initial experiment after starvation for 20 d. 2） The moisture content in muscle of black seabream increased slightly, while protein and ash content in muscle were significantly decreased during the starvation .The protein content decreased to 12.37% of dry body weight after 20-day-starvation, which was significantly different from that of initial experiment （P〈0.05）. There was no difference in lipid content during the starvation （P〉0.05）. The composition of muscle got back to normal after re-feeding for 10 d. The contents of protein and lipid in muscle after 15-day-re-feeding were higher than those in initial experiment. The statistical analysis showed that the black seabream juveniles use lipid firstly and then use protein as the chief energy source to maintain their life during starvation. 3） Total protein, glucose, triglyceride and cholesterol in serum decreased significantly during starvation and got back to normal level after 5-day- re-feeding except the glucose which got the highest after re-feeding for 3 days and then decreased gradually without significant difference （P〉0.05）. 4） The activities of tryptase and lipase in liver increased during starvation, and almost twice the initial experiment after starvation for 20 days, and decreased during re-feeding. After the fish were were re-fed for 20 d, the activities of tryptase and lipase in liver were higher than that of initial experiment. The amylase activity in liver decreased during starvation and increased during re-feeding without obvious change.