BACKGROUND: To reduce adverse environmental effects resulting from repeated use of chemical contaminants, herbal extracts are a natural suitable alternative in aquaculture. Objectives: The present study investigated the effects of Biarum carduchorum and Quercus Infectoria Gall extracts on percentage of hatching and survival rate in the early growth stage of rainbow trout (Oncorhynchus mykiss) larvae compared with malachite green (MG). Methods: To assess the percentage of hatching and survival rate in the early growth stage, B. carduchorum was used at 400 mg/l for 30 minutes per day, Q. Infectoria Gall at 40 mg/l for 30 minutes per day and MG as the positive control at 2 mg/l for 20 minutes per day. Normal control without any treatment was also included. Each treatment trial was provided in three replicates.  Results: The obtained results showed that the mortality level in normal control was significantly higher than other groups in the hatching stage (p<0.05). Also, the mortality rate in eggs treated with B. carduchorum was significantly lower than both MG and Q. Infectoria Gall groups (p<0.05). The mortality rate in eggs treated with Q. Infectoria Gall was significantly higher than MG group (p<0.05). In addition, the mortality rate of the produced larvae was significantly higher in both Q. Infectoria Gall group and normal control groups than the other two groups (p<0.05).Conclusions: The results showed that use of B. carduchorum at 400 mg/L is able to significantly improve the survival rate of rainbow trout eggs and larvae during incubation period. It can be comparable to MG.

Introduction: The goal of this study was to assess the influence of vaccination against enteric redmouth disease on oxidative stress biomarkers and antioxidant defence in the muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) vaccinated against Yersinia ruckeri in the first and second month after immunisation. Material and Methods: Healthy fish were vaccinated orally with inactivated whole cells of a virulent strain of Y. ruckeri. One and two months after immunisation the muscle samples were collected. Results: No significant difference was noted in lipid peroxidation level in either the first or second month after vaccination, while aldehydic and ketonic derivatives of oxidatively modified proteins (OMB) in the vaccinated group were significantly lower in the second month compared to those in the first month after vaccination (P < 0.05). The content of ketonic derivatives of OMB in muscles in the first month after immunisation was higher compared to untreated control. All these culminated in a depletion of glutathione peroxidase (GPx) activity and low level of total antioxidant capacity (TAC). Conclusion: Correlations between catalase activity and lipid peroxidation and TAC confirmed the pivotal role of catalase in antioxidant defence during immunisation. From a broader perspective, it is suggested that immunisation of fish with Yersinia vaccine is associated with induced free radical formation and oxidative stress. Free radicals would therefore be at least partially responsible for the induction of both humoral and cellular elements of the immunity and increased protective immunity against Y. ruckeri infection.

Introduction: The goal of this study was to assess the influence of vaccination against enteric redmouth disease on oxidative stress biomarkers and antioxidant defence in the muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) vaccinated against Yersinia ruckeri in the first and second month after immunisation. Material and Methods: Healthy fish were vaccinated orally with inactivated whole cells of a virulent strain of Y. ruckeri. One and two months after immunisation the muscle samples were collected. Results: No significant difference was noted in lipid peroxidation level in either the first or second month after vaccination, while aldehydic and ketonic derivatives of oxidatively modified proteins (OMB) in the vaccinated group were significantly lower in the second month compared to those in the first month after vaccination (P < 0.05). The content of ketonic derivatives of OMB in muscles in the first month after immunisation was higher compared to untreated control. All these culminated in a depletion of glutathione peroxidase (GPx) activity and low level of total antioxidant capacity (TAC). Conclusion: Correlations between catalase activity and lipid peroxidation and TAC confirmed the pivotal role of catalase in antioxidant defence during immunisation. From a broader perspective, it is suggested that immunisation of fish with Yersinia vaccine is associated with induced free radical formation and oxidative stress. Free radicals would therefore be at least partially responsible for the induction of both humoral and cellular elements of the immunity and increased protective immunity against Y. ruckeri infection.