Characteristics of safety and efficacy of chelate complexes in the Oncorhynchus mykiss model

Rainbow trout Oncorhynchus mykiss is one of the key species in industrial aquaculture. Therefore, studying the biological effects of chelate complexes on survival, productivity indicators, and growth mechanisms is relevant. The aim of the study is to evaluate the safety and effectiveness of various dosages of a chelate complex using Oncorhynchus mykiss as a model. The study used the chelate complex Helavit S (LLC “Yupiter”, Russia). The research was conducted on juvenile Oncorhynchus mykiss . The experiment was conducted over a period of 90 days in an industrial fish farm. Chelate complexes were sprayed onto granulated feed. The weight of the fish sample was assessed (at the beginning of the experiment, on day 45, and on day 90); the data obtained were used to compare the weight gain of the sample. To assess the potential toxic effects of various doses of the chelate complex, morphological studies of the liver were carried out (n=10). The assessment of intestinal proteolytic activity and the relative level of expression were evaluated using a chelate complex at a dosage of 0.5 g/kg of feed for 30 days (n=10). It was established that the use of a chelate complex to enrich the feed of Oncorhynchus mykiss has a dose‑dependent effect on fishery and physiological indicators. The most pronounced effect was observed when the additive was used at a dosage of 0.5 g/kg of feed: the fish’s weight at the end of the experiment exceeded the control value by 11.5%, while no significant differences in survival rates between the experimental and control groups were detected. It has been shown that the use of the complex at a dosage of 0.5 g/kg of feed promotes an increase in the proteolytic activity of the intestinal mucosa, as well as an increase in the relative expression level of the MyHC and MyoG genes in muscle tissue. The observed changes may indicate an enhancement of protein hydrolysis in the feed and the activation of myogenesis mechanisms.