| Feeding and growth are the key issues in the aquaculture industry, because theyare related to success or not. Respiration and excretion are the basic physiologicalactivity of energy metabolism for animal, and they reflect both the physiologicalconditions of the animal and the impact of the culture environment on the animal.Knowing and grasping the respiration and excretion of the turbot plays an importantrole in rational stocking density, feeding and water quality management in breedingprocess, and at the same time can provide theoretical and technical basis for theformulation of turbot health farming system. The study, using orthogonal experimentdesign, was conducted to examine the effects of DO (6.0±1.0mg/L、12.0±1.0mg/L),ammonia (0.01mg/L、0.04mg/L、0.07mg/L、0.10mg/L) and nitrite (1mg/L、5mg/L、9mg/L、13mg/L) on growth and metabolism of juvenile turbot(11.91±1.4g). The paperhas done the following research:①feeding and growth change of the juvenile turbotunder the interaction effect of the three factors were studied, and the regressionanalysis of experimental results were taken and the feeding and growth regressionmodel was obtained;②the oxygen consumption and ammonia excretion change ofthe juvenile turbot under the interaction effect of the three factors were studied, andthe regression analysis of experimental results were taken and the oxygenconsumption rate and ammonia excretion rate regression model was obtained;③arecirculating aquaculture system which can breed40t turbot was designed based onthe research results to compare the investment and benefit in different oxygenationconditions. The main findings are as follows:(1) DO and ammonia had a significant effect on feeding and growth of juvenileturbot (P<0.05) and nitrite did not have a significant effect (P>0.05). The resultsshowed that the feeding rate (FR), weight gain rate (WGR) and specific growth rate (SGR) decreased with the ammonia increasing; but they increased with the DOincreasing. As the time passed by, the growth of juvenile turbot speed up and asignificant difference between groups was appearance. It showed that the turbot needsome time to adapt the ammonia added in the water and can be able to adapt thechange of the environmental factors within a certain range. Increasing DO couldsignificantly reduce the toxic effect of ammonia on the juvenile turbot, improve theenvironment and effectively raise the feeding, growth and feed utilization efficiencyof the juvenile turbot.(2) The feeding rate, weight gain rate and specific growth rate stepwise linearregression models of juvenile turbot under different DO, ammonia and nitrite were:FR（%）=0.576-4.667×FA+0.022×DO (R2=0.952, P<0.01); WGR（%）=67.231-1031.4×FA+4.570×DO (R2=0.951, P<0.01); SGR（%）=0.817-11.69×FA+0.052×DO (R2=0.922, P<0.01)。DO and ammonia were selected in the linear model and nitrite wasnot in. It showed that the concentration of nitrite set in this study had no significanteffect on the feeding rate, weight gain rate and specific growth rate. Because of theseregression equations, the feeding and growth of juvenile turbot in different DO,ammonia and nitrite could be simulated to provide the basis for feeding and growthmanagement of turbot recirculating aquaculture.(3) DO and ammonia had a significant effect on the oxygen consumption rateand ammonia excretion rate of juvenile turbot (P<0.05) and nitrite did not have asignificant effect (P>0.05). The oxygen consumption rate increased with the DOincreasing, and the variation was [（0.1223±0.0136）-（0.2086±0.0103）]mg/(g·h) inthe same ammonia. While with the ammonia concentration increasing, the amount ofthe increase gradually decreased. The oxygen consumption rate increased with theammonia increasing when CNH3-N<0.07mg/L, and dropped significantly whenCNH3-N>0.07mg/L. The variation regulation of the ammonia excretion rate was like theoxygen consumption rate.(4) The relationship of the oxygen consumption rate (RO) and ammonia (FA),weight (g), DO after60days matched the following equation: RO=0.185+0.009DO -1.19FA+0.006T (R2=0.76，F=4.226，P<0.05). The relationship of weight and oxygenconsumption rate can be represented as the power function RO=aW-b, the value of awas4.0596-11.851, and b was0.7419-1.2412. The relationship of the ammoniaexcretion rate (RN) and ammonia (FA), weight (g), DO after60days matched thefollowing equation: RN=13.827+0.256DO-130.51FA+0.056T （R2=0.963，F=34.888，P<0.01）. The relationship of the weight and the ammonia excretion rate can berepresented as the power function RN=aW-b, the value of a was68.759-1977.7, and bwas0.5363-2.0514. The variation of the coefficient showed that the decline of theoxygen consumption rate and the ammonia excretion rate increased with the weightincreasing when the ammonia increasing.(5) The economic analysis of the turbot recirculating aquaculture in different DOwas taken, and the result indicated that raising DO could reduce the input of the feedand the breeding cycle, increase the density and the profits. |
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