Physiological state of the sterlet × beluga hybrid (Asipenser ruthenus × Huso huso) when growing under ecological conditions in the Volga delta

Three-year-olds (15 individuals) and eight-year-olds (15 individuals) of the sterlet × beluga hybrid (Asipenser ruthenus × Huso huso), grown in mesh cages in the Volga delta, were studied in the third decade of September 2019 in order to establish the functional state of the organism by blood parameters reflecting the state erythron and metabolism. The results of the performed study found that the erythron system differs in a smaller number of blood erythrocytes in eight-year-olds (0,76 ± 0,04 × 1012l –1) compared with three-year-olds (0,98 ± 0,04 × 1012l –1), in the absence of differences in blood hemoglobin and serum iron. Analysis of the state of protein metabolism showed that the content of total protein and the activity of ASAT in serum were the same in the groups. The serum albumin content in eight-yearolds was 17,87 ± 0,92 g/l, which was significantly less than in three-year-olds (24,15 ± 1,78) (p < 0,05). The relative content of serum albumin (as a percentage of total protein) in eightyear-olds was 51,04 ± 3,12%, which is less than in three-year-olds (72,51 ± 6,04%) (p < 0.01). The serum ALAT activity in eight-year-olds was lower than in three-year-olds (2,33 ± 0,16 and 2,93 ± 0,17 μkat/l, respectively) (p < 0,05). The results of the study of lipid metabolism revealed that serum cholesterol in eight-year-olds (2,62 ± 0,11 mmol/l) is less than in three-year-olds (1,39 ± 0,05) (p < 0,05). However, the serum triglyceride content did not differ between threeyear-olds and eight-year-olds, being 3,50 ± 0,07 and 3,26 ± 0,13 mmol/l, respectively. The glycemic values in three-year-olds and eight-year-olds are significantly different and amount to 1,80 ± 0,08 and 1,42 ± 0,11 mmol/l, respectively (p < 0.05). The results of the study can be used to assess the state of physiological adaptation of the hybrid and to determine the reference values of the parameters of the erythron system and metabolic homeostasis.