鲜饵不同投饵率对2–5龄大鲵(Andrias davidianus)生长的影响

Effects of Frequency of Feeding with Fresh Diet on the Growth of the 2 to 5-year-old Andrias davidianus

关键词:  大鲵  鲜饵  投饵率  生长

Key words:  Andrias davidianus  Fresh diet  Feeding rate  Growth

摘要:

为探寻大鲵(Andrias davidianus)的适宜投饵率，在水温为18–19℃、pH为8.0和溶氧为6.0 mg/L的工厂化养殖条件下，用鲜饵分别投喂了2、3、4和5龄大鲵各60 d。比较了各实验组体重增加量、全长增加量、饵料系数、平均增重率、特定生长率和饵料转化率等生长指标。结果显示，2龄大鲵的投饵率为2.0%时，其饵料系数均显著低于投饵率为1.7%、2.6%、2.9%的组，其平均增重率和饵料转化率均显著高于投饵率为1.7%、2.3%、2.6%、2.9%的组，其特定生长率均显著高于投饵率为1.7%、2.6%的组(P<0.05)；3龄大鲵的投饵率为2.2%时，其饵料系数均显著低于投饵率为1.9%、2.5%、2.8%的组，其平均增重率和特定生长率均显著高于投饵率为1.6%、1.9%、2.5%、2.8%的组，其饵料转化率均显著高于投饵率为2.5%、2.8%的组(P<0.05)；4龄大鲵的投饵率为2.3%时，其饵料系数均显著低于投饵率为1.7%、2.0%、2.9%的组，其平均增重率和特定生长率均显著高于投饵率为1.7%、2.0%、2.9%的组，其饵料转化率均显著高于投饵率为1.7%、2.9%的组(P<0.05)；5龄大鲵的投饵率为2.5%时，其饵料系数显著低于投饵率为1.9%的组，其平均增重率和特定生长率均显著高于投饵率为1.9%、2.2%、2.8%、3.1%的组，其饵料转化率均显著高于投饵率为2.2%、2.8%、3.1%的组(P<0.05)。为使大鲵的饵料系数较低，平均增重率、特定生长率和饵料转化率较高，研究表明，2、3、4和5龄大鲵的适宜投饵率分别为2.0%、2.2%、2.3%、2.5%；随着大鲵年龄的增加，适宜投饵率呈逐渐增加的变化规律，关系式为y=0.000212x+2.07 (r2=0.8797)。

Abstract:

In this study we aimed to explore the influence of feeding rate on the growth of the Chinese giant salamander Andrias davidianus under certain conditions in industrial aquaculture such as water temperature 18–19℃, pH 8.0 and dissolved oxygen 6.0 mg/L. Chinese giant salamander aged 2, 3, 4 and 5-year-old were fed with fresh dead carp at five different rates, and the corresponding growth rates were recorded during 60 days. We compared a variety of growth traits between different groups including the weight gain, the total length increment, the feed coefficient, the weight gain rate, the specific growth rate and the food conversion rate. Two-year-old Chinese giant salamander with feeding rate 2.0% had a significantly lower feed coefficient but higher weight gain rate and food conversion rate than those fed at 1.7%, 2.3%, 2.6%, and 2.9%. Moreover, its specific growth rate was also higher than that of groups fed at 1.7% and 2.6% (P<0.05). Three-year-old Chinese giant salamander with feeding rate 2.2% had a significantly lower feed coefficient than those fed at 1.9%, 2.5%, 2.8%, but higher weight gain rate and specific growth rate than those fed at 1.6%, 1.9%, 2.5% and 2.8%. Their food conversion rate was significantly higher than those fed at 2.5% and 2.8% (P<0.05). Four-year-old Chinese giant salamander with feeding rate 2.3% had a significantly lower feed coefficient but higher weight gain rate and specific growth rate compared to those fed at 1.7%, 2.0% and 2.9%, and its the food conversion rate were significantly higher than those fed at 1.7% and 2.9% (P<0.05). Five-year-old Chinese giant salamander fed at 2.5% had a significantly lower feed coefficient than those fed at 1.9%, higher weight gain rate and specific growth rate than those fed at 1.9%, 2.2%, 2.8% and 3.1%, and higher food conversion rate than those fed at 2.2%, 2.8% and 3.1% (P<0.05). In order to reduce the feed coefficient and to raise the weight gain rate, specific growth rate and food conversion rate, we recommended that the appropriate feeding rates should be 2.0%, 2.2%, 2.3% and 2.5% for 2, 3, 4 and 5-year-old Chinese giant salamander respectively. The optimal feeding rate appeared to increase along with growing age, which conformed to equation y=0.000212x+2.07 (r2=0.8797).