Determination of the effects of thin-skinned plum (prunus domestica) extract on immune response of rainbow trout (oncorhynchus mykiss) against enteric redmouth disease (yersinia ruckeri)

In this study, changes in immune responses of rainbow trout (Oncorhynchus mykiss) fed with thin-skinned plum (Prunus domestica) aqueous methanolic extract and also its protective efficacy against enteric redmouth disease (Yersinia ruckeri) were investigated. For this purpose, the fish were fed diet containing thin-skinned plum extract doses of 0% (Control), 0.1%, 0.5% and 1% ad libitum twice in a day. Blood and tissue (spleen, intestine and anterior kidney) samples were taken from the fish 7, 14, and 21. days of the study and changes in immune and cytokine gene responses of fish were determined. Yersinia ruckeri was intraperitoneally injected at the end of the study and the survival rate of the fish was recorded for 10 days. While there was an increase in the oxidative radical release of the fish in the 1% group on the 7th day (P <0.05), no difference was observed in the other sampling periods (P>0.05). Bacterial killing activity was also found to increase significantly in the 1% group (P<0.05) and on the 21. day of the study, this group showed a decrease (P<0.05). While lysozyme activities did not change during any sampling period (P>0.05), myeloperoxidase activity increased in all groups on day 14 compared to control group (P<0.05). Cytokine gene expression elevated on the 7th day of the study in the kidney and intestine. Feed conversion ratio was significantly decreased on the 1% group. It was not observed any histopathologically adverse effects on the fish fed with thin-skined plum extract. All experimental group's challenge results showed an increased survival rate against Yersinia ruckeri (P<0.05). In the light of all these results, it was concluded that thin-skinned plum can be used as immunostimulant in rainbow trout against Yersinia ruckeri.