池塘循环水槽养殖模式下吉富罗非鱼的生长及生理响应变化

为探讨在池塘循环水槽养殖模式下吉富罗非鱼不同养殖密度的生长特性和生理指标变化,评估吉富罗非鱼在池塘循环水槽养殖模式下的适宜养殖密度,以吉富罗非鱼为实验对象,设计传统池塘养殖模式放养密度5尾/m~2 (SD1组),池塘循环水槽养殖模式放养密度180尾/m~2 (SD2组)和270尾/m~2 (SD3组),比较各组吉富罗非鱼的生长性能,分析血液生化指标和肝脏HSP70 mRNA表达量的变化规律。结果显示,经过120 d的养殖,SD2组吉富罗非鱼终末体质量、特定生长率和绝对生长率显著高于SD1和SD3组。SD2和SD3组存活率、体质量差异系数和饵料系数低于SD1组。SD2组血清皮质醇、血清谷丙转氨酶、谷草转氨酶、溶菌酶水平和肝脏HSP70 mRNA的相对表达量在30 d时显著高于SD1组。SD3组血清皮质醇和葡萄糖水平在60 d后持续上升,120 d时显著高于SD1组,谷丙转氨酶、谷草转氨酶、溶菌酶水平和肝脏HSP70 mRNA的相对表达量在60、90 d时显著高于SD1组,甘油三酯在整个实验期显著低于SD1组。SD2组吉富罗非鱼在养殖前期受到环境胁迫,中后期适应环境;SD3组在养殖中后期受到环境胁迫,长期处于应激状态。吉富罗非鱼生长和血清生理指标,池塘循环水槽养殖吉富罗非鱼的适宜养殖密度为180尾/m~2,在该密度下罗非鱼能适应养殖环境,养殖效果优于传统养殖模式。

Growth and physiological responses of GIFT Oreochromis niloticus in an in-pond raceway system

To investigate the variety of different stocking density growth performance and physiological indices, evaluate the suitable stocking density of tilapia in pond aquaculture system. Taking GIFT tilapia as the research object, the traditional pond culture model was designed as the control group A (5 tails/m₂), In pond aquaculture system was designed as the control group B (180 tails/m₂) and C (270 tails/m₂). The results show that after 120 days of breeding, final body weight, specific growth rate and absolute growth rate of tilapia in group B were significantly higher than those in group A and C (P<0.05); group A had the highest survival rate and group C had the lowest survival rate; Coefficient of variation of weight and the feed coefficient of the test group were smaller than the control group. The glutamic-pyruvic transaminase, glutamic-oxaloacetic transaminase, lysozyme level and hepatic Hsp70m RNA levels initially increased and then decreased during aquaculture. The levels of cortisol and triglyceride in the test group B were different from in the control group A throughout the culture prophase (P<0.05), glucose levels did not differ from the control group throughout the culture cycle. Cortisol and glucose levels in the test group C continued to increase (P<0.05), and the triglyceride levels did not differ throughout the culture cycle. The test group B tilapia was exposed to environmental stress in the early stage of cultivation, and gradually adapted to the environment in the middle and late stages; test group C was under stress throughout the culture cycle. The result suggested that suitable stocking density of tilapia cultured in pond aquaculture system is 180/m₂. In this density tilapia farming can adapt to the environment, and cultivation effect is superior to the traditional farming mode.