菊黄东方鲀当年鱼种养殖阶段消化酶活性研究

为了研究池塘养殖菊黄东方鲀（Takifugu flavidus）鱼种生长及肠组织中消化酶活性随生长的变化，2012年5－11月进行室外养殖试验，池塘面积0.2 hm2，水深1.5～2.0 m，鱼苗体长1.2~1.5 cm，放养密度为22.5 万尾/hm2，试验用海水盐度5~15，水温为15~35℃，pH 8~9；测定当年鱼种不同生长阶段的体长、体质量、肝重、肠长等生长指标，通过生物化学方法测定了其肠组织主要消化酶活性。结果表明，菊黄东方鲀幼鱼体长、体质量与养殖天数均呈指数相关（L=27.07e0.0088t, W=1.0982e0.0262t）；体长与体质量呈幂函数增长相关（W=3×10-5L3.1070），且为异速生长。不同生长阶段菊黄东方鲀肝体比、比肠长、肥满度的变化显著（P<0.05）；肝体比随生长呈显著上升趋势（P<0.05），变化范围为4.15%~20.23%；比肠长则呈显著下降趋势（P<0.05），变化范围为0.97%～2.33%，不同生长阶段肥满度变化为3.99%～5.11%。菊黄东方鲀肠组织碱性蛋白酶和淀粉酶活性均随生长呈显著降低趋势（P<0.05），最大值均出现在养殖40 d（83.11 U/mg与3.13 U/mg）；酸性蛋白酶活性呈先下降、后上升趋势（P<0.05），最小值（0.34 U/mg）与最大值（0.86 U/mg）分别出现在113 d和166 d；脂肪酶活性随生长变化不显著（P>0.05）。研究表明，菊黄东方鲀鱼种的生长与养殖条件的改变存在密切关系；肝体比、比肠长等与鱼的发育及营养摄入存在一定关系；肠组织不是生成蛋白酶和淀粉酶的主要器官。

Digestive Enzyme Activity of Juvenile Tawny Puffer (Takifugu flavidus) Cultured in Ponds

Digestion is a key process in fish metabolism because it determines the availability of nutrients needed for all biological functions, so research on digestive physiology is important. Furthermore, the activity level of digestive enzymes reflects the nutritional condition and adaptation to dietary change for fish at different growth stages. This study was carried out in outdoor ponds from May to November 2012 with the aim of investigating the growth of juvenile tawny puffer at different stages and the changes in digestive enzyme activity in intestinal tissue. The culture pond was 0.2 hm2 with water depth of 1.5-2.0 m, temperature range of 15-35oC, pH 8-9 and salinity of 5-15 g/kg. On May 31, 2012, the 27-day-old puffer larvae (1.2-1.5 cm) were placed in the culture pond at a density of 22.5×104 ind/hm2 and on August 2, the 90-day-old juveniles were deconcentrated into other ponds and 5000 juvenile fish were kept in the test pond. Beginning with the 40th day of culture, 30 fish were sampled to obtain measurements of total length and body mass on a cycle of 12-18d. Then the 30 fish were randomly assigned into three groups to determine the hepatic weight, intestine length and the intestinal tissue were sampled to determine the activity of intestinal digestive enzymes using biochemical methods. The relationship of total length or body mass to culture days was well described by exponential functions: L=27.07e0.0088t, W=1.0982e0.0262t. Body mass was then correlated with total length using a power function: W=3×10-5 L3.1070, under artificial farming conditions, and growth in mass was allometric with total length. The ratio of hepatic weight to body mass (HSI), intestine length to body length (RLB) and the condition factor (CF) changed significantly for different growth periods (P<0.05). HSI increased significantly with the growth of Tawny Puffer (P<0.05) and ranged from 4.15% to 20.23%, while RLB decreased significantly (P<0.05), and ranged form 0.97% to 2.33%. The range of CF at different growth stages was 3.99%-5.11%. The activities of alkaline protease and amylase in intestinal tissue decreased significantly with Tawny Puffer growth (P<0.05) and both reached maximum levels (83.11 U/mg and 3.13 U/mg) on d 40. Acid protease activity rose initially and then decreased with minimum (0.34 U/mg) and maximum (0.86 U/mg) values measured on d 113 and d166, respectively. Lipase activity did not change significantly (P>0.05. There appears to be a link between HIS, RLB and nutrition during Tawny Puffer development. Intestinal tissue is not the main organ for generating protease and amylase and the data suggests that fish growth is closely linked to changes in culture conditions.