Evaluation of the effectiveness of the use of the probiotic Natupro to increase natural resistance and prevent infectious diseases of fish

The paper presents the results of a scientific experiment on two-year-old carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss) and sterlet (Acipenser ruthenus), performed based on RUE “Institute of Fisheries” RUE “Scientific and Practical Center of the National Academy of Sciences of Belarus on Animal Husbandry”. The aim of the research was to study the effect of the probiotic Natupro on the natural resistance of fish and the possibility of its use for the prevention of infectious diseases. Probiotic Natupro was added to the diets of two-year-old carp, rainbow trout and sterlet in dosages of 500 and 800 g/ton of feed. The use of the additive at a dosage of 500 g/t of feed provided an increase in the bactericidal activity of blood serum in sterlet and carp by 38.4% (p < 0.05) and 38.4% (p < 0.05), respectively, relative to the control values. The sensitivity of pathogenic strains of bacteria-pathogens of fish Yersinia ruckeri, Shewanella putrefaciens, Aeromonas salmonicida, Aeromonas hydrophila, Pseudomonas fluorescens and Pseudomonas protegens to the effects of the additive Natupro was revealed. In experiments with experimental infection of fish with Aeromonas salmonicida No. 56, it was found that the use of probiotics in dosages of 500 and 800 g/ton of feed reduced the death of trout by 80%, sterlet by 70–90%, carp by 50–90%.