室内循环养殖系统中曝气流量对尼罗罗非鱼生长的影响

曝气流量是曝气推流循环养殖系统的重要控制性因素,为综合研究不同曝气流量对鱼类生长和鱼肉品质的影响,参照野外养殖基地,利用自行设计的室内循环流水养殖模型,在0、30和50 L/min三组曝气条件下,以尼罗罗非鱼[初始体质量为(23.61±3.50)g]为对象,进行为期56 d的研究。结果显示:①30 L/min组中尼罗罗非鱼的最终体质量和特定生长率分别为(79.56±3.82) g和(2.81±0.54)%/d,其中特定生长率比0和50 L/min组分别高出11.07%和8.49%,同时该曝气流量下血清中的总蛋白和甘油三酯浓度较高,而尿素氮浓度较低,比如第56天时总蛋白浓度比0和50 L/min组分别高出57.43%和10.43%,甘油三酯浓度则分别高出22.19%和12.32%,但尿素氮浓度降低了39.02%和37.50%。葡萄糖浓度受曝气流量影响不显著。50 L/min组谷丙转氨酶和谷草转氨酶活性高于0和30 L/min组;②第56天时30 L/min组中鱼肉的硬度、弹性和咀嚼性高于0和50 L/min组,硬度分别比0和50 L/min组高出27.10%和15.85%,弹性高出9.1...

Influence of aeration flow rates on Oreochromis niloticus growth in indoor recirculating aquaculture system

Aeration flow rate is the crucial controlling factor for aerated push-flow recirculating aquaculture system, in order to explore the effects of aeration flow rates on fish growth and flesh quality, a 56-days experiment was conducted with self-designed indoor recirculating aquaculture system model under 3 aeration flow rates (0 L/min, 30 L/min and 50 L/min, respectively), where the growth performance and flesh quality of tilapia (Oreochromis niloticus) were measured. The results showed: (1) The final body weight and specific growth rate of tilapia in the 30 L/min condition were 79.56±3.82 g and 2.81±0.54 %/d, while the specific growth rate was 11.1% and 8.49% higher than that in the 0 L/min and the 50 L/min conditions. At the same time, the total protein and triglyceride concentrations in the 30 L/min condition were higher but the urea nitrogen concentration was lower, e.g., on the 56^th day, the TP concentrations were 57.43% and 10.43% higher than those in the 0 L/min and 50 L/min conditions, as for TCHO concentration, the increments were 22.19% and 12.32%, respectively. However, the BUN concentration decreased by 39.02% and 37.50%. Furthermore, the glucose concentration was not significantly affected by the aeration flow rates, but the alanine aminotransferase and aspartate aminotransferase concentrations in the 50 L/min condition were higher than those in the other conditions; (2) The hardness, springiness and chewiness of the fish in the 30 L/min condition were significantly higher than those in the 0 L/min condition on the 56^th day, e.g., the hardness was 27.10% and 15.85% higher than that in the 0 L/min and 50 L/min conditions, as for the springiness and the chewiness, the increments were 9.10% and 3.54%, 42.25% and 24.06% respectively, but the resilience was slightly higher in the 50 L/min condition than that in the other groups. Through analysis of test results, the growth rate of tilapia was slow due to lack of water stimulation and dissolved oxygen concentration at the small aeration flow rate (such as 0 L/min), while the consumption of nutrients of tilapia was accelerated in the large aeration flow rate (such as 50 L/min), only at the moderate aeration rate flow (such as 30 L/min), the tilapia attained better growth performance and flesh quality.