Effects Of Enrofloxacin And Cortisol On The Immune Function And Intestinal Microflora Of Chinese Mitten Crab (Eriocheir Sinensis)

So far, the research about effects of enrofloxacin and cortisol on the immune functionand intestinal microflora of crustacean has not been reported. The procedure of thisexperiment was as follows: Chinese mitten crab (Eriocheir sinensis) were fed with basalfeed which contains enrofloxacin or cortisol at different dose of0(control),50,100and200mg/kg and for7days, separately. After starting the experiment, taked sample from1st,4th, and7th day to check the change of immunology parameters and intestinalmicroflora. Crabs were challenged at2×107colony forming units (cfu)/kg crab weightwith a virulent strain of Aeromonas hydrophila (CL99920) of E. sinensis at7days afteradministration of levamisole, and mortalities were recorded over a7day period.The result showed that:(1) After feeding crabs on enrofloxacin of50,100and200mg/kg for7days, the total haemocyte count (THC), haemocyte phagocytic activity, therespiratory burst activity (release of superoxide anion), the serum parameters, includingacid phosphatase (ACP) and alkaline phosphatase (AKP) activity of50mg/kg groupshowed a remarkable higher number compared to control group (P<0.05). And thosewere the same with the AKP activity of serum of100mg/kg group, the aspertateaminotransferase(GOT) and alanine aminotransferase (GPT) activity of serum of100mg/kg group and200mg/kg group, and the total antioxidant capacity (T-AOC) andsuper oxide dismutase (SOD) activity of serum of all three groups. However, the THC,haemocyte phagocytic percentage, phagocytic index, respiratory burst activity,phenoloxidase (PO), peroxidase (POD) and lysozyme (LSZ) activity of serum of100mg/kg group and200mg/kg group showed a remarkable lower number compared tocontrol group (P<0.05). Bacillus of50mg/kg group increased sharply, but aerobicbacteria, Aeromonas and Escherichia were quite opposite (P<0.05), and anaerobicformers were almost the same as that of control group (P>0.05). All kinds of microflorashows a remarkable lower number compared to control group (P<0.05). After virulent strain of A. hydrophila, the mortality of50mg/kg group was lower than that of controlgroup, but the mortality of200mg/kg group was20%higher than that of control group.(2) After feeding crabs on cortisol of50,100and200mg/kg for7days, the SODactivity of serum of50mg/kg group and100mg/kg group, T-AOC、AKP、GOT andGPT activity of serum of all three groups wree much higher than those of control group(P<0.05). The LSZ and ACP activity of serum of100mg/kg group and200mg/kggroup, and the THC, haemocyte phagocytic percentage, phagocytic parameters,respiratory burst activity, PO, and POD activity of serum wre much lower than those ofcontrol group (P<0.05). There was no remarkable effect on intestinal microflora of E.sinensis which were fed on test dose of cortisol (P>0.05). And after virulent strain of A.hydrophila, the mortalities of all three experimental groups were much higher than thatof control group, and that of200mg/kg group waas the highest,26.67%higher than thecontrol group.