Status of the antioxidant protection system of carp organism after feeding with amaranth (Amaranthus Linnaеus, 1753) in standard and stressed rearing conditions

Purpose. To determine the efficiency of using amaranth (Amaranthus) in carp feeding under standard rearing conditions and under the effect of stress-factors common in aquaculture, in order to activate the antioxidant protection system of their organism. Methodology. Fishery and hydrochemical studies were conducted according to generally accepted methods. The protein content was determined by the Bretford method. The concentration of diene conjugates was studied using a method based on the reaction of the optical density of a heptane isopropanol lipid extract. Determination of the concentration of TBA-active products was carried out spectrophotometrically by a color reaction with thiobarbituric acid. The activity of superoxide dismutase (SOD) was determined as the percent of the inhibition of nitrosin tetrazolium reduction reaction in the presence of phenazine methosulfate. Catalase activity was determined by changing H2O2 concentration. Findings. The research was conducted in the aquaria room of the Institute of Fisheries NAAS. The effect on the antioxidant protection system activity of the organism of carp yearlings after addition of amaranth to their diet in the amount of 10% has been analyzed. Rearing was carried out under standard conditions and under the effect of stress-factors that are common for fish culture: pollution of the aquatic environment caused by the introduction of intensification measures; complex contamination of water with simultaneous decrease in the dissolved oxygen content. The research showed that the additional feeding of amaranth to carps under standard conditions of cultivation, there was a certain tendency to an increase in the content of SOD in muscle and hepatopancreas (by 5.9–8.3%) and to an increase in the content of lipid peroxidation products (by 14.3–15.7%). The effect of stress factors showed more marked tendencies. Thus, in polluted water, the activity of SOD in muscle significantly increased (p˂0.01), at the same time, the content of diene conjugates (p˂0.01) increased. In hepatopancreas, a tendency to a 2.9% increase in the activity of catalase and a 44.1% decrease in the content of diene conjugates was observed. Under the complex effect of stress factors, the activity of catalase and TBA-products in muscles tended to decrease, diene conjugates tended to increase, while SOD increased (p˂0,01). In hepatopancreas, there was a tendency to an increase in the content of catalase and SOD, respectively, by 16.5% and 5.9%. At the same time, the content of products of lipid peroxidation — TBA products (p˂0,01) and diene conjugates (p˂0,001) reduced. Originality. The analysis of anti-oxidant properties of amaranth and the degree of the effect of feeding this additive to carp yearlings on the antioxidant protection system activity of their organism under standard conditions of cultivation and the effect of stress-factors common for aquaculture have been analyzed. Practical value. Supplementation of carp diet with amaranth in production conditions can be used as a way to reduce the degree of adverse effects of common environmental stress-factors (contamination as a result of intensive measures and decrease in dissolved oxygen content in water to critical values) on the functional state of fish organism by increasing the antioxidant protection system activity.