Effects of dietary supplementation of propolis on some of the health indicators in rainbow trout (Oncorhynchus mykiss)

Objective: Propolis is a natural product derived from plant resins collected by honeybees. Its complex chemical composition includes more than 180 compounds and it has various biological activities, namely anticancer, antioxidant, anti-inflammatory, antibiotic, antifungal and antihepatotoxic. Due to the lack of information about the possible effects of propolis on health status of rainbow trout, in this study some of the well-known indicators widely used in fish health studies, including haematocrit (Hct), haemoglobin (Hb) concentration, serum total protein (TP) concentration, glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and lactic dehydrogenase (LDH) activities in serum were examined. Method & Materials: Propolis was dissolved in ethanol and added to diets. Juvenile rainbow trout (mean initial weight 14 g) were fed on experimental diets (3% of biomass per day) supplemented with 0(control), 0.5, 1.5, 4.5 and 9 g propolis/Kg diet for 8 weeks (four replicate tanks for each treatment). At the end of the experiment, blood samples were collected from 4 fish per replicate for haematological and serum biochemical analysis. Hct was determined, using a microhaematocrit centrifuge. Hb was measured by the cyanohaemoglobin method. Mentioned serum biochemical parameters were measured with an automated analyzer (Roche COBAS MIRA). Results & Conclusion: The lowest values of Hb and Hct were observed in fish fed with control diet. Hb and Hct values were significantly higher in groups receiving 4.5 and 9 g propolis/Kg diet than that of control group (p < 0.05). There were no significant differences in TP concentrations among the experimental groups. GOT, GPT and LDH activities in serum did not show significant differences among the five groups; however GPT values in fish fed with 9 g propolis/Kg diet were lower than other groups. It is possible to hypothesize that propolis complex composition may lead to damage in the organism but the present study revealed that dietary supplementation of propolis ethanolic extract has no adverse effects on tested biochemical parameters of health and also can enhance mentioned blood indices in rainbow trout. Due to the versatile biological activities of propolis, further studies are needed on other possible physiological effects of this substance on fish.

کلیدواژه ها:

Propolis ، Rainbow trout (Oncorhynchus mykiss) ، Health ، Blood indices ، Serum biochemical parameters