Productivity and efficiency of growing age-1+ carp (Cyprinus carpio (Linnaeus, 1758)) with the use of a prebiotic additive in the feed composition

Purpose. The aim of the work was to assess the effectiveness and feasibility of using the prebiotic "Actigen" in the process of commercial cultivation of carp taking into account productive and economic indicators. Methodology. The study was conducted in 2019, using three ponds, two of which were experimental and one control, which were stocked with age-1 scaly carp with an average weight of 55 - 56 g at a stocking density of 1000 specimens/ha. Carp of the experimental groups were fed during 90 days of the growing season with a feed with supplemented with the prebiotic "Actigen" at the amount of 0.025% (Experiment 1) and 0.05% (Experiment 2). Optimal conditions for carp keeping were provided during the study with the control of oxygen, temperature, hydro-chemical and hydro-biological regimes of the aquatic environment and analysis of the efficiency of cultivation at the end of the growing season according to generally accepted methods in aquaculture. Piscicultural and economic indicators of age-1+ carp cultivation were determined at the end of the growing season. Findings. Conditions for growing carp in experimental and control ponds were satisfactory. No dependence of the hydro-chemical regime of experimental ponds on the composition of the diet was found. The average seasonal biomass of food organisms of zooplankton and zoobenthos during the growing season was 10.81 – 20.64 g/m3 and 0.47 – 0.73 g/m2, respectively, and served as an additional source of food for carp. It was found that the average weight of age-1+ carp, which was fed with the feed with the addition of 0.025% and 0.05% of prebiotic supplements, was higher by 11.9% and 22.2%, respectively, fish productivity – by 12.1% and 23.1%. The feed conversion rate was lower by 9.5% and 19.1% relative to the control. The cost of additionally obtained fish products when fish were fed with a feed supplemented with the prebiotic at the amount of 0.025% was 4290 UAH/ha, 0.05% - 8190 UAH/ ha. The contingent income, including costs for feeds and fish seeds using 0.025% and 0.05% prebiotic, was 20.9% and 33.6% higher, respectively, than in the control group. Originality. The effect of prebiotic "Actigen" on productivity and economic indicators in the process of growing age-1+ carp was studied for the first time. The implementation of this task provided an opportunity to increase the fish productivity of ponds by feeding fish with an artificial feed of improved composition. Practical value. The obtained results testify to the expediency and efficiency of using prebiotic "Actigen" in fish farming. Reducing the cost and obtaining additional gains in the cultivation of fish products is provided by improving the quality characteristics of feed.