Efficiency of use of prebiotics based on manane oligosaccharides in carp feeding

Purpose. Analysis of productive and economic indicators in the cultivation of age-1+ carp as a result of the use of prebiotics based on mannan oligosaccharides (MOS) in feeding. Methodology. Four ponds were used, two of which were experimental and two control ponds, which were stocked with age-1 scaly carp with an average weight of 76–77 g at a stocking density of 2200 specimens/ha. Fish of Experiment 1 and Control 1 were fed with extruded feed with a protein content of 23%, fish in Experiment 2 and Control 2 were fed with a grain mixture with a protein content of 19%. 0.05% prebiotic based on MOS "Actigen" was added to the diet of experimental groups of carp throughout the growing season. Optimal conditions for carp farming were ensured including control over oxygen, hydrochemical and hydrobiological regimes in ponds, which were measured according to the generally accepted methods in fish farming. Fishery and economic indicators of growing age-1+ were determined after harvesting fish in autumn. Findings. Major hydrochemical parameters in all ponds were within the normative values. The average seasonal biomass of forage organisms of zooplankton and zoobenthos during the growing season did not differ in the experimental ponds and amounted to 10.33-16.23 g/m3 and 1.23-2.96 g/m3. A positive effect of the use of prebiotics based on MOS in the feeding of age-1+ carp was established. When the prebiotic was given as a part of the extruded feed, the average weight of fish was higher by 11.5%, and fish productivity by 22.7% relative to the control group, while the cost of feed for cultivation was lower by 20%. When it was added to the grain mixture, these values were higher by 12.9%, 16.3% and 16.7%, respectively. The profit, as a result of the use of the prebiotic based on MOS in the composition of the extruded feed increased by 43.3% compared to Control 1, and by 19.1% compared to Control 2 when it was added to the grain mixture. Originality. For the first time, a comparative analysis of the effectiveness of the use of the prebiotic based on MOS in the composition of extruded feed and grain mixtures was performed taking into account productivity and economic indicators. Practical value. The obtained results indicate the feasibility and effectiveness of the use of prebiotics based on MOS in the feeding of age-1+ carp. Introduction of experimental additives to feeds of different composition helps to obtain additional growth and increase the economic component in the cultivation of carp to marketable condition.