Effects of propolis, a honeybee product, on growth performance and immune responses of Barbus barbulus

Propolis, a honeybee product, has been used empirically for centuries and was always mentioned as an immunomodulatory. In this study, the effects of propolis on growth indices, innate immune responses and haematological parameters of Barbus barbulus were investigated. Three hundred and sixty juvenile Barbus barbulus, weighing 102±8.2g were randomly divided into four equal groups in triplicate. Groups 1 to 3 were fed basal food supplemented with 0.1, 0.5, 1% of Propolis-ethanolic -extract (PEE) in diet for 60 days. Control group received basal diet free of PEE. At the end of experiment, growth indices were measured in all groups. Various immunological parameters (serum lysozymme and bactericidal activity, complement activity, total serum protein and globulin) as well as hematological parameters (RBC, WBC, hemoglobin, hematocrit, MCV, MCH and MCHC) of Barbus barbulus were compared among the groups. Then the fish were challenged with Aeromonas hydrophila. Oral administration of different level of PEE induce no significant change, neither in growth indices nor in haematological parameters of B. barbulus (p>0.05). Significant increase in serum Lysozyme and bactericidal activity, total serum protein and WBC were seen in G2 and G3 compared to the control group (p<0.05). Meanwhile, mortality after challenge of fish fed on diet containing 0.5% PPE significantly decreased compared to control group. It was concluded that, although supplementation of food with 0.5 and 1% PEE enhanced some immune response indicators of B.barbulus, growth indices and hematological parameters were not affected by this supplementation.