中文摘要：

为了研究饲料钙水平对淡水养殖鲈Lateolabrax japonicus血清渗透压、离子水平以及与渗透压调节有关酶活力的影响,以体质量为（12.47±0.01）g的鲈为研究对象,分别投喂钙水平为0.29%（D1）、0.42%（D2）、0.65%（D3）、0.79%（D4）、1.02%（D5）、3.10%（D6）的6种等氮等能饲料,共饲养8周。结果表明：随着饲料中钙水平的提高,D1、D2组血清渗透压无显著性差异（P〉0.05）,均显著高于D3、D4和D5组（P〈0.05）,与D6组无显著性差异（P〉0.05）;血清Na＋水平和Cl-水平的变化趋势相似,均随着饲料钙水平的提高呈先上升后降低的趋势（P〈0.05）,其中D1、D2和D6组血清Na＋和Cl-水平均低于其他各组,血清Ca2＋水平D5组最高,D6组最低,其他各组均无显著性差异（P〉0.05）;随着饲料中钙水平的提高,鳃丝Na＋/K＋-ATP（NKA）酶活力呈先降低后升高趋势,D1组酶活力最高（P〈0.05）,而Ca2＋-ATP（CA）酶活力总体呈降低趋势,也以D1组酶活力最高（P〈0.05）,肠道中NKA酶活力呈先上升后降低趋势,D3组酶活力最高（P〈0.05）,肠道中CA酶活力D1和D3组较高,D6组最低,肾脏中NKA酶活力和CA酶活力均随着饲料中钙水平的提高呈先降低后升高的趋势,NKA酶活力D1组最高,D4组最低,而CA酶活力D1、D3组较高,D4组最低。研究表明,低钙饲料（0.29%和0.42%钙水平）和高钙饲料（3.10%钙水平）均会使淡水养殖鲈处于高强度的渗透压调节状态,而含钙0.65%~1.02%的饲料有利于其渗透压平衡调节。

英文摘要：

A feeding trial was conducted to investigate effects of dietary calcium（Ca） levels on serum osmolality,serum ion levels and activities of relative enzymes regulating osmolality in Japanese seabass Lateolabrax japonicus cultured in freshwater.Japanese seabass juveniles with body weight of（12.47 ± 0.01） g were fed six iso-nitrogenous and iso-energetic diets containing calcium（Ca） of 0.29%（D1）,0.42%（D2）,0.65%（D3）,0.79%（D4）,1.02%（D5） and 3.10%（D6） for 8 weeks.The results showed that there was significantly higher serum osmolality in groups D1 and D2 than that in groups D3,D4 and D5（P 〈 0.05）,without significant difference among groups D1 and D2 and group D6（P 〉 0.05）.Serum Na＋and Cl-levels were shown to be increased and then decreased as dietary Ca levels increased（P 〈 0.05）,lower in D1,D2 and D6 groups than those in other treatments.The maximal serum Ca2 ＋level was observed in group D5 and the minimal value in group D6,without significant difference among other groups（P 〉 0.05）.With the elevation of dietary Ca level,the Na＋/ K＋-ATPase（NKAase） activity in gill was decreased and then increased,the maximum in group D1（P 〈 0.05）,while the Ca2 ＋-ATPase（CAase） activity was significantly decreased and the maximum also in group D1（P 〈 0.05）; the intestinal NKAase activity was increased first and then decreased and reached the highest value in group D3（P 〈 0.05）,and the higher intestinal CAase activity appeared in groups D1 and D3 and the minimum in group D6.The activities of NKAase and CAase in kidney were all decreased first and then increased as dietary Ca levels increased,the maximal kidney NKAase activity in group D1 and the minimum in group D4,however the higher CAase activity was in groups D1 and D3 and the minimum in group D4.Japanese seabass fed the low Ca diets（0.29%,and 0.42%） and the high Ca diet（3.10%） both showed high osmotic regulation,and the diets containing 0.65%-1.02% Ca will be benefit for the osmotic