高密度养殖凡纳滨对虾的蛋白质生态营养需要量

在高密度养殖条件(平均养殖密度3.1kg/m3)下,用5种蛋白质水平(31%、35%、39%、43%、47%,分别以A～E组表示)的饲料,投喂体质量(6.2±0.2)g的凡纳滨对虾(Litopenaeus vannamei),每个处理组设3个重复,每个重复30尾虾,实验期60d,探讨蛋白质营养对生长、环境因子、排泄与饲料消化特征的影响。结果表明:(1)饲料蛋白水平39%时具有显著促进对虾生长的效果。随着蛋白水平的提高,增重率先增加后降低,饲料系数则相反。(2)养殖水体中氨氮、亚硝氮和磷酸盐浓度随饲料蛋白质水平增加而显著升高,E组与其他各组差异显著(P0.05)或极显著(P0.01)。(3)随着饲料蛋白质含量增加,饲料总消化率显著下降,而蛋白质消化率显著升高(。4)创新建立的对虾日粮蛋白质水平与日增氮、日排有害氮的定量动态变化关系,使蛋白质生态营养需要量得以量化确定。高密度养殖凡纳滨对虾获得最大增重的蛋白质需要量为43.73%,获得最佳生长和氮减排的蛋白质需要量为40.42%。

Eco-nutrition requirement of protein in high density Litopenaeus vannamei culture system

An experiment was conducted for 60 days to determine the relationship between different dietary protein levels and growth performance,environment factors and digestive characteristics of white shrimp Litopenaeus vannamei in high density culture system.Four hundred and fifty white shrimps with average initial weight of (6.2±0.2)g were assigned randomly to five treatments groups with three replicates and were fed diets with 5 different protein levels which were 31%,35%,39%,43% and 47%,respectively in average stock density of 3.1 kg/m~3.The results were as follows:(1)As the protein levels increased,the weight gain rate rose at first and then decreased,while the feed conversion ratio had the opposite tendency.Shrimps fed with 43% dietary protein got the best growth performance.(2)Seawater factors such as NH_4~+-N,NO_2~——N,PO_4~(3-)-P and suspended substance (SS)were affected significantly by dietary protein levels(P＜0.05),and all of them increased with protein levels increasing.The environmental factors of the group fed with 47% dietary protein were different from those of other groups significantly(P＜0.05).(3)Total apparent digestion rate decreased with the increase of protein level,while the protein digestion rate increased significantly(P＜0.05).(4)We have innovatively qualified the dynamic relationship between nitrogen excretion or nitrogen gain and the increasing dietary protein levels,so that the exact requirement of protein can be calculated.Based on the growth performance,43.73% may be recommended as the conventional requirement of protein with the biggest growth rate for adult white shrimps in high density culture system.However,40.42% may be recommended as the eco-nntrition requirement of protein with the optimum growth and nitrogen excretion.