A preliminary study on the feeding effect of the red swamp crayfish (Procambarus clakii) using biofloc technology

To investigate the possibility of feeding the red swamp crayfish (Procambarus clarkii) with biofloc technology, a 30-day short-term experiment was conducted to farm juveniles (9.70±0.32) g using biofloc technology and feeding normal diet. This experiment compared the hydrochemical indexes of two experimental groups during experimental period and compared 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 (N\rmO_2^ - -N), nitrate nitrogen (N\rmO_3^ - -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 P. clarkii. However, the crude lipid content of biofloc was significantly lower and affected the crude lipid content of muscle from biofloc group juveniles. The α-amylase (α-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 α-AL activity in stomach and intestine was 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 significantly 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 farming of the red swamp crayfish. And this technology could achieve the same or even better affect than the normal diet feeding.