盐度对花鳗鲡和太平洋双色鳗鲡幼鳗生长性能及消化酶活力的影响

文章研究了不同盐度对花鳗鲡(Anguilla marmorata)幼鳗和太平洋双色鳗鲡(A. bicolor pacifica)幼鳗生长性能及消化酶活力的影响。将花鳗鲡幼鳗(9.760.36) g和太平洋双色鳗鲡幼鳗(11.820.04) g分别在淡水(盐度0)与盐度5、10、18水体中养殖30d, 测量每组实验鱼总重后检测胃、肠道和肝脏蛋白酶、淀粉酶和脂肪酶的活力。结果表明, 花鳗鲡和太平洋双色鳗鲡在各盐度处理中存活率均为100%, 未出现死亡。两种鳗鲡在淡水中生长良好, 特定生长率最高, 而饵料系数最低。盐度对花鳗鲡幼鳗和太平洋双色鳗鲡幼鳗消化酶活力的影响存在差异, 其中花鳗鲡胃、肠道和肝脏蛋白酶活力在各盐度处理中均无显著变化(P0.05), 淀粉酶和脂肪酶活力均随盐度的增加而下降; 太平洋双色鳗鲡胃蛋白酶活力在盐度10时最大, 肝蛋白酶活力在盐度18时最大, 而淀粉酶和脂肪酶活力在各盐度处理组无显著变化(P0.05)。这表明盐度对花鳗鲡胃、肠道和肝脏的淀粉酶和脂肪酶活力具有抑制作用, 对太平洋双色鳗鲡的蛋白酶活力有一定的激活作用。在相同盐度条件下, 不同消化器官中同种消化酶活力存在差异, 各盐度的两种鳗鲡肠道中淀粉酶和脂肪酶的活力均显著高于肝脏和胃(P0.05), 胃中蛋白酶活力高于肝脏和肠道, 但不显著(P0.05)。研究发现两种鳗鲡体内脂肪酶活力相对较高, 表明其对脂肪具有较强的消化能力。建议在配制花鳗鲡幼鳗和太平洋双色鳗鲡幼鳗饲料时, 适当提高粗脂肪比例, 有助于促进对营养物质的消化吸收, 提高养殖效益。  

EFFECTS OF THE SALINITY ON THE GROWTH PERFORMANCE AND DIGESTIVE ENZYME ACTIVITIES OFANGUILLA MARMORATA ELVER AND A. BICOLORPACIFICAELVER

In this study, we investigated the effects of salinity on the growth and the activities of the digestive enzymes of Anguilla marmorata elver body weight (9.76 0.36) g and A. bicolor pacifica elver body weight (11.82 0.04) g. Subjects of the two species were cultured at four salinities (0, 5, 10 and 18) for 30 days. We first weighed all the eels in each tank, and then analyzed three types of digestive enzymes (protease, amylase and lipase) in three digestive organs (liver, stomach and intestine) of both species. The results showed that the survival rates of the two species were both 100% in all four salinities with no death case. In fresh water both species exhibited excellent growth performance, the highest specific growth rates (SGR), and the lowest food conversion ratios (FCR). The effects of salinity on the digestive enzyme activities were different between the two species. In the three digestive organs, the salinity did not significantly affect the activity of protease in A. marmorata elver (P0.05), but the increase in salinity caused reduced activities of amylase and lipase. For A. bicolor pacifica elver, the highest activity of protease in the stomach and the liver appeared at the salinities of 10 and 18 respectively; whereas the salinity did not affect the activities of amylase and lipase in the three digestive organs (P0.05). We deducted that saline water could inhibit the activities of amylase and lipase in the liver, the stomach and the intestine of A. marmorata elver, but might increase the protease activity of A. bicolor pacifica elver. At the same salinity the same digestive enzymes in different digestive organs showed different activities. For both species the activities of amylase and lipase in the intestine were significantly higher than in the liver and the stomach (P0.05); the activity of protease in the stomach was insignificantly higher than in the liver and the intestine (P0.05). Our study suggested that the high activity of lipase enabled A.marmorata elver and A. bicolor pacifica elver to digest fat efficiently. Therefore it may be suitable to increase the portion of the crude fat in the compounding feed, which could boost the digestion and absorption of nutrients and thus improve the quality of aquaculture.