Effect of probiotic “Subalin” on the productive parameters of age-0+ sturgeon hybrid (Acipenseridae) — bester under conditions of thermal load

Purpose. To determine the effect of adding the probiotic “Subalin” to the diet under conditions of elevated water temperature on productive parameters of age-0+ bester. Methodology. Experimental studies were carried out in the summer-autumn period of 2024 in the conditions of tanks of the “Biosyla” farm created using heated waste water from an energy facility. Hybrid sturgeon Bester at the age of 0+ were grown for 50 days with feeding with feed of recommended formulations with a crude protein content of 54% and crude fat of 15% with the addition of the probiotic preparation “Subalin” to the diet. The studied probiotic was added to the feed at the rate (% of the feed weight): 0.04 (variant 1) and 0.03 (variant 2). For control, an identical feed without the addition of a probiotic was used. The stocking density of fish with an average body weight of 70.5 g at the beginning of the studies (second decade of August) was 100 ind. per tank (56 ind./m2). The assessment of growth, survival, and productivity parameters of bester and the analysis of physicochemical factors of the aquatic environment were carried out using methods common in fish farming. Findings. The water temperature in tanks with juvenile bester during the experiments ranged from 28.1 to 33.7°C, which was 5.0 to 5.5°C higher than during the same period in water bodies with the natural temperature regime of the Forest-Steppe zone. The oxygen concentration in the water was within 3.5 to 5.4 mg O2/dm3. Other hydrochemical parameters in the tanks did not significantly exceed the standard values ​​and were typical for water bodies in the region. As a result, after 50 days of cultivation, age-0+ bester at the end of the third decade of September reached an average weight of 248.5 g in the variant with a share of the “Subalin” in the feed of 0.04% and 259.5 g when adding this preparation to the feed in an amount of 0.03%. In the control, the average body weight of the fish was 212.4 g, which was 14.5–18.1% less than in the experimental variants. In both variants of the experiments and the control, 100% survival of fish was recorded. During the entire period of cultivation, the absolute and relative daily gains of the fish of both experimental groups were higher than those of fish of the control group. A preliminary conclusion was made on the feasibility of adding the probiotic “Subalin” to the standard formula feed during the cultivation of age-0+ bester under conditions of heat stress in the amount (% of the feed weight): 0.04 - for fish with an average weight of 20–70 g and 0.03 - for fish with an average weight of more than 70 g. Originality. The conducted studies on the effect of the probiotic “Subalin” on the productive parameters of age-0+ bester are part of similar studies launched in 2023. In the conditions of sturgeon farming using heated waste water from an energy facility, studies in this area are being carried out for the first time. Pactical Value. The obtained results are of interest for the development of sturgeon aquaculture in industrial-type farms, in particular at elevated water temperatures in conditions of climate change.