| Popis: |
Nowadays, medical plants extract is used in aquaculture industry to enhance growth, immune system and fish resistance to different pathogens. In this study, some non-specific immune responses, hematology and biochemical parameters in rainbow trout juveniles (16 gr mean weight) and their resistance to Streptococcus iniae were evaluated following oral administration of Echinacea purpurea and Astragalus sp. extract. Three concentrations (0.5, 1 and 1.5 gr/kg of feed) of Echinacea purpurea and three concentrations (2, 3 and 5 gr/kg of feed) of Astragalus sp extract and control group were used for 60 days. Parameters evaluated included: levels of C4, C3 (complement components), free oxygen radicals (respiratory burst), Lysozyme, numbers of lymphocytes, monocytes and neutrophils. In the end, the relative survival rate (RSR) of fish was evaluated against S. iniae. The results showed that the levels of C3, lysozyme, oxygen free radicals, the number of neutrophils and lymphocytes in the experiment groups (the highest dose) compared to control group were increased significantly (p 0.05). The relative survival rates of fish following challenge with Streptococcus iniae, were 91/11, 93/33 and 44/44 percent in experiments (Echinacea purpurea and Astragalus sp.) and control groups, respectively. In conclusion, it may be state that Echinacea purpurea and Astragalus sp. extracts enhance the non-specific immune system and fish resistance against Streptococcusis, and it seems it can be used as immunostimulant in feed. |
