Determination of alternative medicinal plants could be used as immunostimulant and therapeutics in gilthead sea bream (Sparus aurata) culture

In this study, it was aimed to determine the effects of nettle (Urtica dioica) and green olive tree (Phillyrea latifolia) ethanolic extracts, which are used as feed additives, on growth performance, hematological parameters and natural immune responses in sea bream (Sparus aurata). In addition, the effects on the survival rate against Vibrio (Listonella) anguillarum pathogen were determined at the end of the stinging nettle experiment. In the study, nettle and green olive tree ethanolic extracts at the rates of 0 mg/kg (control); 50mg/kg; 100mg/kg; 200 mg/kg and 400 mg/kg were added to the feeds, and the experiment was carried out in sea bream fish for 60 days. As a result of the experiments established separately for each plant; It has been determined that nettle and green olive tree extracts stimulate immunity without having a negative effect on growth performance and blood parameters such as red blood cell, hematocrit and hemoglobin. As a result of the addition of plants to the food at different doses, there were significant increases in lysozyme and myeloperoxidase activities (p<0.05); It was also determined that there was an increase in respiratory burst activity, which can only be achieved for nettle extract (p<0.05). As a result of the control test, which can be performed only for nettle, it was determined that the ethanolic extract of nettle added to the feed at a concentration of 100 mg/kg provided a 96% survival rate against the Vibrio (Listonella) anguillarum pathogen in sea bream. In both plant experiments, changes in the expression levels of genes responsible for immunity (IL-1β; IL-6, IL-10, IL-18 and TNF-α) and humoral responses were discussed and the results were evaluated. As a result, the use of 100 mg/kg nettle or 200 mg/kg or 400 mg/kg green olive tree ethanolic extracts as feed additives resulted in a significant activation of immunity in sea bream fish.