封闭循环水养殖半滑舌鳎蛋白质的生态营养需要量

Effects of eco-nutrition requirement of protein on Cynoglossus semilaevis Günther in industrial culture with seawater quality and digestive enzyme

研究在封闭循环水养殖条件下,选用半滑舌鳎幼鱼(110±25)g,进行5×3双因素试验,即5种饲料蛋白质水平(43%、46%、49%、52%、56%,以A～E组表示)和3种饲喂饱食度水平(100%、90%、80%,以Ⅰ、Ⅱ、Ⅲ水平表示),分为15个处理组,每个处理3重复,每个重复25尾鱼,试验期108d。通过生长、水质、消化酶等指标测定,研究蛋白质营养与饱食度对工厂化养殖半滑舌鳎生长和养殖水环境的影响。结果表明,(1)随蛋白质水平和饱食度升高,增重率显著提高(P<0.01),E组显著高于其它组13.75%～50.16%,Ⅰ水平比Ⅱ、Ⅲ水平分别显著提高7.57%、14.08%;E组饲料系数显著低于其它各组6.25%～27.44%(P<0.05),但饱食度对饲料系数的影响没有前者对其影响显著,Ⅰ与Ⅱ水平差异不显著,Ⅰ水平比Ⅲ水平显著高5%;鱼体氨氮、亚硝氮、总有害氮(氨氮+亚硝氮)的排泄率显著增加(P<0.01),C组(中蛋白水平)总有害氮比E、D组分别降低64.40%、54.50%,Ⅰ水平分别比Ⅱ、Ⅲ水平极显著高17.8%、29.2%;(2)随蛋白水平升高,肝脏和肠道蛋白酶活力增强,E组比其它各组提高10.50%～81.23%(肝)及6.84%～48.90%(肠)。脂肪酶活力降低,E组比其它各组降低2.46%～14.36%(肝)及4.31%～20.58%(肠)。淀粉酶活力先增加后降低,肝脏淀粉酶活力C组最高,且比其它组高8.53%～22.27%,肠道中B组活力最高,比其它组高5.3%～21.93%。随饱食度升高,肝脏和肠道中消化酶活力各组均降低,Ⅲ水平蛋白酶、脂肪酶、淀粉酶活力比Ⅱ、Ⅲ水平分别降低5.23%～18.07%、6.62%～18.76%和3.91%～10.64%;(3)通过日增氮量与日总有害氮排泄量的回归分析与模拟测算,获得饱食度Ⅰ、Ⅱ、Ⅲ水平的蛋白质生态营养需要量分别为48.30%、49.27%和50.67%。生态适宜性饱食度为90%。

The experiment was conducted to determine effects of protein levels and satiation degrees on juvenile Cynoglossus semilaevis Günther in industrial culture conditions with closed recirculation seawater.The 5 × 3 two-factor random animal experiment lasted for 108 days,total of 1125 fish[with initial weight（110 ± 25） g]were randomly allotted into 15 treatments with triplicates,25 fish each replicate,5 protein levels diets（43% ,46% ,49% ,52% ,56% ,with A-E） ,3 satiation degrees feeding（100% ,90% ,80% ,withⅠ,Ⅱ and Ⅲ） .Evaluated effects of different protein levels and satiation degrees on juvenile C.semilaevis growth performance,seawater environment factors and digestive enzyme.The primary results showed that： （1） As the protein level of feed and satiation degree increased,weight gain increased significantly（P 0.01） ,the best weight gain both in the highest protein level and the highest satiation degree.Weight gain ratio in group E was significantly higher than the other groups by 13.75%-50.16% ,that in degree Ⅰ was 7.57% and 14.08% higher than degree Ⅱand Ⅲ .The best feed conversion ratio appeared in the highest protein level,which was significantly higher than the other groups by 6.25%-27.44% （P 0.05） ,but satiation degree didn’t have such significant impact on FCR as protein level did： there was no significant difference between degreeⅠ and Ⅱ,and Ⅰ did better on FCR than Ⅲ significantly（P 0.05） .As the protein level and satiation degree increased,NH 4＋-N,NO 2-N excretion and total baneful nitrogen excretion were enhanced（P 0.01） .The total baneful nitrogen excretion in group C was 54.5% and 64.4% lower than group D and E respectively,that in degree Ⅰ was 17.8% and 29.2% higher than Ⅱand Ⅲ ,respectively;（2） The activity of protease enhanced,lipase reduced and amylase increased at first,then reduced with increased protein level.As satiation degree increased,digestive enzyme reduced.digestive enzyme of liver was higher than intestine;（3） The relationship between nitrogen excretion and the weight gain as the increasing dietary protein levels,partially accorded with the Rhomb character.By regression analysis,the optimum eco-nutrition requirement of protein for juvenile C.semilaevis seemed to be 48.30% ,49.27% and 50.67% ,respectively in degree Ⅰ,Ⅱ and Ⅲ.The optimum eco-aquatic requirement of satiation was 90% .