Effects Of Bioflocs On Cultured Water,Growth,Antioxidant Enzymes And Digestive Enzymes Of Macrobrachium Nipponense

Macrobrachium nipponense is an important freshw-ater cultured shrimp in China.The Macrobrachium nipponense culture has developed to a higher level.However,with the expansion of the scale of cultivation,there are more and more problems in actual production,and the degree of intensification is increasing.The resulting diseases and pollution have affected the production of Macrobrachium nipponense.Under the background of promoting green farming and protecting ecology,the improvement of farming technology has become a new development direction of aquaculture.Biofloc technology is a healthy farming technology that is ecologically sound and has not been applied to Macrobrachium nipponense.Therefore,this study used Macrobrachium nipponense as a research object to analyze the production of bioflocs under different carbon-nitrogen ratios and the effects of ammonia nitrogen,nitrite nitrogen concentration and colony structure in water.The effects of the growth performance of Macrobrachium nipponense and the evaluation of the digestive enzymes and antioxidant enzymes of Macrobrachium nipponense were as follows:1.Different carbon-nitrogen ratios on the formation of bioflocs and the effects on aquaculture waters:Five groups were set up in this experiment,which were control group without carbon source,carbon/nitrogen ratio 10(C/N10)group,and carbon to nitrogen ratio.(C/N15)group,carbon to nitrogen ratio 20(C/N20)group,carbon to nitrogen ratio 25(C/N25)group.The results show that(1)biofloc content C/N20>C/N25>C/N15>C/N10,C/N20 biofloc group is the most,while C/N10 has almost no biofloc production,C/N15 and C./N25 has a small amount of biofloc,but the content is lower than C/N20.(2)The concentration of ammonia nitrogen and nitrite nitrogen in the control group continued to increase,and the concentrations of ammonia nitrogen and nitrite nitrogen in C/N10 and C/N25 fluctuated greatly,first increased and then decreased,and then increased.C The ammonia nitrogen and nitrite concentrations of C/N15 and C/N20 were maintained at a low level throughout the culture period without significant fluctuations.(3)Analysis of colony structure of water bodies showed that Proteobacteria,Bacteroidetes,Actinobacteria and Firmicutes were the dominant species in the water body,of which Proteobacteria Content Control>C/N20>C/N 15>C/N25>C/N 10,Actinomycete contentC/N20>C/N15>C/N10>C/N25>Control;The content of Bacteroides and Firmicutes increased continuously with the increase of carbon to nitrogen ratio.From the analysis of the level,the content of Bacillus in C/N15,C/N20 and C/N25 increased significantly(P<0.05).Compared with the control group,the Clostridium content of C/N20 was significantly decreased(P<0.05).The results show that maintaining a carbon to nitrogen ratio of 20 can increase the content of beneficial bacteria,reduce the content of harmful bacteria,and maintain the stability of water colony structure.2.Effect of bioflocs on the growth performance of Macrobrachium nipponense:Carbon sources were added to the aquaculture water according to different carbon-nitrogen ratios 10,15,20,and 25.The control group did not add and regularly drained water.The results showed that:(1)Weight gain rate is C/N20>C/N25>C/N15>C/N10>Control,C/N10,C/N15,C/N20 and C/N25 were 29.69%,50.22%,89.52%,and 75.98%,respectively(P<0.05).The specific growth rate was C/N20>C/N25>C/N15>C/N10>Control.C/N10,C/N15,C/N20,and C/N25 were 18.41%,24.69%,42.26%,and 33.89%higher than the control group,respectively(P<0.05).In terms of survival rate,C/N20>C/N15>Control>C/N10>C/N25,there was no significant difference between the control group,C/N10 and C/N15.Compared with the control group,the survival rate of C/N20 was significantly increased(P<0.05),while C/N25 was significantly lower.In the control group(P<0.05).(2)In terms of antioxidant enzymes,glutathione peroxidase(GPX)activity C/N20>C/N25>C/N15>C/N10>Control,compared with the control group,C/N10,C/N15,C/N20,C/N25 were 1.70%,21.42%,43.19%,and 31.49%higher,respectively(P<0.05);superoxide dismutase(SOD)activity C/N20>C/N25>C/N15>C/N10>Control,compared with the control group,C/N10,C/N15,C/N20,C/N25 were 19.34%,35.26%,73.35%,47.12%higher respectively(3)in terms of digestive enzymes.The amylase activity was C/N20>C/N15>C/N25>Control>C/N10.Compared with the control group,C/N15,C/N20 and C/N25 were 68.09%,23 1.11%and 42,55%(P<0.05);the lipase activity was C/N20>C/N25>C/N15>Control>C/N 10,compared with the control group,C/N15,C/N20,C/N25 were higher respectively 2.86%,25.45%,23.12%(P<0.05);trypsin activity was C/N20>C/N25>C/N15>C/N10>Control,compared with the control group,C/N10,C/N15 The C/N20 and C/N25 groups were 12.98%,14.52%,36.45%,24.63%(P<0.05).This study shows that bioflocs can effectively improve the growth performance,increase the antioxidant enzyme and digestion enzyme of Macrobrachium nipponense,and the optimal carbon to nitrogen ratio should be kept at 20.