Results of the use of a sorbent in a carp feed with signs of mycotoxin contamination

Purpose. The aim of the work was to study certain morpho-physiological parameters of carp as a result of additional introduction of a mycotoxin sorbent to a feed with signs of spoilage. Methodology. During 2019–2020, two experiments were conducted in the laboratory. The first one included 7 groups-analogues of age-1+ Nyvky carp, 20 fish in each group, with an average weight of 22.5 g. The control group of fish was fed for 24 days with a compound feed with signs of spoilage, «Mykosorb» was additionally added to the diet of the experimental groups in the amounts of 0.05, 0.1; 0.15; 0.2; 0.25 and 0.4%, respectively. The second group included 4 groups of age-1+ fish, 12 fish in each group, with an average weight of 20.0 g. The diet of the control group was identical to that of the first experiment, and the experimental groups with the addition of 0.05, 0.075 and 0.1% of «Mycosorb», respectively. During the study, optimal conditions for keeping fish were provided. Fish after were measured and weighed at the end of the experiment and their weight gains were analyzed according to generally accepted methods in fish farming. The activity of antioxidant enzymes and the content of lipid peroxidation products depending on the composition of the diet were studied. Findings. The studies used compound feed with signs of spoilage as a result of violation of their storage technology, which identified three groups of toxins: Aflatoxin B1, Zearalenone and Deoxynivalenol. As a result of the first stage of the study, the rates of application of mycotoxin sorbent into the diet of carp at amounts of 0.05 - 0.2% were determined. At the same time, there was no clear proportional pattern of changes in the average weight of fish depending on the amount of introduction of «Mycosorb», the value increased in all experimental groups compared to the control by 0.4 – 15.2%. Muscles of age-1+ fish were found to have higher (p<0,001) catalase activity after application of 0.15% of the test drug by 1.4 times, 0.2% — by 46%, 0.25% — by 69 and 0.4% — by 79%. Superoxide dismutase activity also increased, except for the groups of 0.2, 0.25 and 0.4% of «Mycosorb». There was a tendency of 21.0 and 22.6% decrease in the content of diene conjugates as a result of feeding 0.05 and 0.1% sorbent and some increase as a result of feeding 0.15; 0.2; 0.25 and 0.4% additives. Studies of the next stage showed that addition of «Mykosorb» at the rate of 0.05, 0.075 and 0.1% to the feed, the average weight of age-1+ carp in the experimental groups increased by 45.4; 37.2 and 30.3%, the condition factor — by 41.9; 40.8 and 42.7%, the relative growth rate is 4.3; 5.9 and 4.6 times, respectively. The fish body height to length ratio was lower by 10.3, 7.0 and 7.4% relative to the control group. Addition of 0.05, 0.075 and 0.1% of «Mycosorb» increased resistance of fish due to an increase in the hepatopancreatic activity of antioxidant enzymes: superoxide dismutase by 28.3, 30.5 and 5.0% and catalase by 56.5 (p<0.001), 55.5 (p<0.001) and 46.3% (p<0.05). At the same time, addition of 0.05 and 0.1% of «Mykosorb» increased the content of diene conjugates by 11.3 (p<0.01) and 12.3% (p<0.01), TBC-active products by 19.7 (p<0.05) and 13.2%. Originality. For the first time, the feasibility of addition of the mycotoxin sorbent «Mykosorb» into the feed with signs of spoilage was studied. The effect of feeding age-1+ carp with diets of various compositions on some morpho-physiological parameters of carp in the conditions of model tests was carried out. Practical value. Additional weigh gains and improvements of the antioxidant defense system of the carp organism were observed. The use of «Mykosorb» in carp feeding allows reducing the negative impact of low quality feed on fish body.