Investigation of in vivo therapeutical effects of Cotinus coggygria plant extract against Aeromonas hydrophila in rainbow trout (Onchorhynchus mykiss)

In this study, therapeutical effects of aqueous methanolic extracts of tetra (Cotinus coggygria) against Aeromonas hydrophila in rainbow trout (Onchorhynchus mykiss) were investigated. Four different concentration of extract (0 mg/100 µl (Control), 4 mg/100 µl, 8 mg/100 µl, 12 mg/100 µl) and also to compare results two different type of antibiotic such as florfenicol and doxycycline were given orally using feeding needle to the each individual in all experimental group twice in a day after intramuscular inoculation of A. hydrophila. The study was pursued during 10 days. Every 0, 3rd, 7th and 10th day of the study, blood was collected from caudal vein of the fish and added to K3EDTA contained blood tubes, and changes in humoral immune responses and hematology of the fish were determined. In the study, superoxide radical realizing was decreased generally in all experimental group except 12 mg Tetra and Florfenicol compared to control (P<0.05). Lysozyme activity was generally decreased (P<0.05) or not differences observed in all experimental group compared to control (P>0.05). Myeloperoxidase was significantly showed the highest value in Florfenicol group at the 7th day of the sampling time (P<0.05). Generally myeloperoxidase was showed an increase in almost all experimental groups. Some hematological parameters in experimental groups were increased. However this increase was not significant. Survival rate of the groups was found in control group as %53.33. There were no significant differences between control and 4 mg Tetra group (P>0.05). All the other groups' survival rate was significantly increased compared to control. The highest survival rate was found in Florcenicol group (80 %). 12 mg Tetra group, Doxycycline and 8 mg Tetra group survival rate was investigated as 74.44 %, 70% and 70 % respectively. According to our results, tetra methanolic extract is an effective therapeutic against A. hydrophila infection in rainbow trout at the dose of 24 mg/32,34g body weight/day.