奥尼罗非鱼仔稚鱼饲料中适宜蛋白质水平的研究

Study on the optimum protein level in dietary of tilapia larvae(Oreochromis niloticus×O.aureus)

为研究奥尼罗非鱼仔稚饲料中最适蛋白质水平,采用蛋白质水平分别为25%、30%、35%、40%、45%、50%和55%的7种饲料投喂奥尼罗非鱼仔稚鱼28d。结果表明:(1)随着饲料蛋白质水平升高,增重率先升高,在45%到达最高值,随后又逐渐下降,45%组显著高于其他各组。通过对饲料蛋白质水平和增重率的二次回归分析表明,饲料蛋白质含量在43%时,罗非鱼仔稚鱼有最大的增重率。特定生长率变化趋势与增重率相似。(2)随饲料蛋白质水平的升高,鱼体蛋白质含量显著升高,而脂肪含量显著下降,高蛋白组(50%、55%组)鱼体灰分显著高于低蛋白组。(3)当日粮蛋白质水平为25%～45%时胃蛋白酶和淀粉酶随饲料蛋白质水平的升高而上升,在饲料蛋白质水平45%时活性最高,且显著高于其他各组(P<0.05);当饲料蛋白质水平高于45%后,蛋白酶、淀粉酶活性显著下降。脂肪酶在饲料蛋白质水平为25%时有最大活性,且活性随饲料蛋白质水平的升高而显著下降,在饲料蛋白含量55%时活性最低。

Seven dietary protein levels （25 %,30 %,35 %,40 %,45 %,50 % and 55 %）were conducted to investigate the optimum dietary protein requirement of tilapia larvae （Oreochromis niloticus xO.aureus ）.The trail lasted 28 days. The results showed：（ 1 ）Weight gain ratio increased firstly,maximum value of 45 % dietary protein level,then decreased with the increase level of dietary protein,and 45 % dietary protein level diet was significant higher than the others. Quadratic regression analysis of weight gain rate against dietary protein levels indicated that the optimal dietary protein requirement for maximum weight gain of the tilapia Oreochromis niloticus xO.aureus was 43 %.The variation trend of specific growth rate was similar to that of the weight gain rate. （2）With the increase level of dietary protein,the protein content of the gross body of the tilapia larvae was increased significantly ,but crude fat of gross body decreased significantly.Ash of gross body in the high dietary protein groups （50 % and 55 %）was higher significantly than that of the low dietary protein groups. （3）The pepsin activity and the amylase activity were both increased when the dietary protein levels were from 25 % to 45 % ,and were maximum in 45 % dietary protein level diet （P 〈 0.05）,then were both reduced significantly when the dietary protein levels were from 45 % to 55 %.However,lipase activity was decreased significantly with the dietary protein levels increase,was maximum at 25 % dietary protein level, but it was minimum in 55 % dietary protein level.