Immune Responses and Haematological Parameters Changes of Rainbow Trout (Oncorhynchus mykiss) under Effects of Dietary Administration of Sumac (Rhus coriaria L.)

The purpose of this study was to evaluate the effect of sumac (Rhus coriaria L.) administration on the growth performance, immune response, and haematological parameters of rainbow trout (Oncorhynchus mykiss). Rainbow trout juveniles with an initial weight of 38±2.65 g were allocated into 12 tanks at a density of 15 fish per tank. Fish were fed four experimental diets containing 0% (as control diet), 0.5%, 2%, and 5% sumac-supplementation for 56 days. After the feeding trial, fish were challenged with Yersinia ruckeri, and survival rate was calculated for 15 days. Sumac diet significantly increased resistance to the pathogen and led to the control of infection in rainbow trout without changing weight. The leukocyte (WBC) and erythrocyte (RBC), lymphocyte, monocyte, and neutrophil value was significantly higher in fish that were fed a sumac-supplemented diet when compared with the control. Serum lysozyme, and alternative complement pathway haemolytic activity (ACH50) as well as the hepatic expression of TNF-α and IL-1b were recorded to be the highest in fish fed 2% and 5% sumac-supplement. Meanwhile, mRNA expression levels of IL-10 significantly decreased in fish fed 5% sumac supplementation for 56 days. These results suggest that sumac administration, especially 2% and 5%, may effectively enhance the immune system, resistance to the pathogen, and hematopoiesis in rainbow trout.