The aim of our study was to evaluate the effect of propolis on mortality of fish eggs due to mycosis, to study its efficacy on the fish growth rate and to analyze the histochemical and ultrastructural characteristics of muscle fibres. We evaluated the muscular development of fish in two different experimental conditions: traditional feeding and feeding with addition of propolis (groups A and B, respectively). The study was carried out on two species of teleosts bred in Italy, Oncorhynchus mykiss (rainbow trout) and Salmo trutta (brown trout). The use of propolis reduced mortality of fish eggs. The muscles were stained for myosin ATPase and succinic dehydrogenase to evaluate fibre type. The area, maximum and minimum diameter for each fibre type in relation to the body length were measured. The animals fed propolis showed a more rapid muscular growth compared to control fed the standard diet. Fibres were larger in the Salmo trutta than in the Oncorhynchus mykiss in both groups. In fish of A group, myotomal muscle, the presence of giant fibres and index of environmental stress was noticed. This type of study is valuable in order to extend the use of propolis as an antifungal agent and a natural product that can improve fish farming.
ATPase and SDH activities, specific growth-rate, ultrastructural analysisEuropean aquaculture has shown a steady increase during the last twenty years, thanks to many initiatives promoted by the European Community to support this sector. But there are still many problems to solve, such as the support of ecocompatible activities, the improvement of animal health and welfare, product quality and consumer health assurance. Propolis is a mixture of various amounts of beeswax and resins collected by the honeybee from plants, particularly from flowers and leaf buds (Krell 1996). The colour of propolis ranges from yellow to dark brown depending on the origin of the resins. Propolis has attracted the researchers' interest in the last decades due to its biological and pharmacological properties, such as immunomodulatory, antitumor, antimicrobial, antiinflammatory, and antioxidant properties (Kanbur et al. 2009). The goal of this study was to analyze, for the first time, the influence of propolis on the fish muscular development and on the structural and ultrastructural characteristics of muscle fibre types. This study opens a new perspective on the investigation of biological properties of propolis, mainly with respect to the influence on the development of the trout and the mortality of fish eggs.
Materials and MethodsThe following species of freshwater fish were used in our study: Salmo trutta (brown trout) and Oncorhynchus mykiss (rainbow trout).
Experiment with eggsIn order to evaluate the effect of propolis on mortality of fish eggs, approximately 600 eggs (half and half) were placed in 3 "Californian tanks" arranged in cascade. Untreated samples (about 250 eggs) were used as control. The eggs were rinsed in propolis solution (1%) for 15 min, once every four days and then they were ...