Study On The Culture Of Red Swamp Crayfish (Procambarus Clarkii) Using Biofloc Technology

Biofloc technology is a healthy and environmentally friendly farming technology that has the advantages of maintaining good water quality,reducing the feed coefficient,enhancing the digestive enzyme activity,antioxidant level,yield and survival rate of farmed animals.However,the application of biofloc technology to Procambarus clarkii has not been reported.In this study,the combination of biofloc technology and P.clarkii culture was conducted to investigate whether the crayfish can feed on bioflocs and the optimal feeding concentration and conditions.Compared with commercial diet feeding,juvenile swamp digest emzyme was compared after a short-term cultured.Antioxidant and immune status and growth performance and nutritional quality of juveniles after a long-term cultured.It is preliminarily confirmed that the biofloc technology can be applied to the culture of P.clarkii,and it shows a good farming effect.This results also lays a foundation for the application of biofloc technology to intensive farming of crayfish.1.Effects of different conditions on feeding biofloc of the red swamp crayfish juvenilesIn this experiment,the suitable biofloc conditions for the red swamp juveniles feeding were discussed from the feeding environment?aeration,no aeration,and aquatic plants?,feeding duration and the biofloc concentration.The results show that 500-600 mg·L-1 biofloc concentration can meet the demand of juveniles,and intestine of the fed juveniles are saturated after 4hours of feeding.Under the same feeding duration,juveniles from the group with aeration have the highest food intake,significantly higher than the group with aquatic plants,but there are no obvious differences between the non-aerated group.Comparing the fullness rank of intestine of each group,the group with aeration has more chyme after 4 hours of feeding.Considering the culture conditions of biofloc,hydrochemical index as well as the feeding of red swamp crayfish juveniles,it is feasible to apply biofloc technology to the culture of the red swamp crayfish.2.A short-term farming of the red swamp crayfish using biofloc technologyThis experiment Compares the hydrochemical indexes of two experimental groups during experimental period and compares the growth performance,muscle and hepatopancreas nutrient composition,the digestive enzyme activities in stomach,intestine,hepatopancreas tissues,the antioxidant capacity in hepatopancreas and muscle tissues of two groups juveniles at the end of the experiment.The results showed that the concentration of total nitrogen?TN?,nitrite nitrogen?NO₂^--N?,nitrate nitrogen?NO₃^--N?of the biofloc group were all kept at a low level during experimental period.The final weight of the juvenile shrimps,the weight gain rate?WG?,the specific growth rate?SGR?and survive rate?SR?showed no significant difference in the two experimental groups under this experiment condition.The content of crude protein of the biofloc was 36.8%which could meet the protein requirement of crayfish.However,the crude lipid content of biofloc was significant lower and affected the crude lipid content of muscle from biofloc group juveniles.The?-amylase??-AL?,Lipase?LPS?and cellulase?CL?activities in hepatopancreas of the biofloc group juveniles were significantly higher than that of the diet group juveniles,respectively,while?-AL activity in stomach and intestine were higher in the diet group.No significant difference was found in the pepsin activity between the two experimental groups.Comparing the antioxidant capacity of crayfish juveniles from the two experimental groups,the activity of superoxide dismutase?SOD?in hepatopancreas of juveniles from the biofloc group was significant higher,and the content of malondialdehyde?MDA?was much lower than that from the diet group.No differences were found in the activities of total antioxidant capacity?T-AOC?,catalase?CAT?,glutathione reductase?GR?and lysozyme?LZM?in hepatopancreas of juveniles from two experimental groups.In conclusion,the biofloc technology had a positive effect on breeding of the red swamp crayfish.And this technology could achieve the same or even better affect than the normal diet feeding.3.A long-term farming of the red swamp crayfish using biofloc technologyA 60-day study comparing the growth performances,proximate compositions and the digestive,immunity,and antioxidant enzyme activities,edibe tissues fatty acids and amino acids cantent of red swamp crayfish?Procambarus clarkii?juveniles reared using biofloc technology?the biofloc group?or a commercial diet?the control group?in zero-water-change indoor tanks was performed.After 60 days feeding,the final weight,weight gain,and specific growth rate for the biofloc group were significantly higher than those for the control group.Furthermore,proximate composition analysis showed that the hepatopancreas total lipid and ash contents of the biofloc group significantly higher than those of the control group.The digestibility and antioxidant immunity of crayfish in the biofloc group were better than those in the diet group.There was no significant difference in muscle collagen content between the two experimental groups,but the water retention of the crayfish muscles in the bioflc group slightly better than the diet group.In addition,the composition and content of fatty acids and amino acids in the edible tissues of juveniles in two groups were compared.It was also found that the fatty acid composition and content of the cultured animals had a certain correlation with the foods they ingested.The fatty acid composition of bioflocs showed the fatty acid composition of the edible tissues of juvenile crayfish.The amino acid composition of bioflocs and diet differed greatly,this did not affect the amino acid composition of the edible tissues of crayfish.There is no difference between the amino acid content of muscle and hepatopancreas from the crayfish in each experimental group.