Physiological state of the hybrid Russian sturgeon × Siberian sturgeon (Acipenser gueldenstaedtii × Acipenser baerii) grown in cages in the Volga delta

Abstract

Three-year-olds (15 individuals) and six-year-olds (15 individuals) of the hybrid Russian sturgeon × Siberian sturgeon (Acipenser gueldenstaedtii × Acipenser baerii), grown in net cages in the Volga delta, were studied at the end of the fishbreeding season in order to establish the functional state of the body according to a set of indicators of the erythron and metabolism. The results of the study revealed that the erythron system in six-year-old ROLO hybrids is characterized by a lower content of erythrocytes and blood hemoglobin (0.37±0.02 × 10¹²/l and 51.32±1.38 g/l, respectively), compared with three-year-olds (0.47±0.03 × 10¹²/l and 59.08±2.38 g/l, respectively) (p < 0.05). The content of serum iron in the groups of three-year-olds and six-year-olds did not differ (15.05±0.62 and 14.63±0.42 µmol/l, respectively) (p > 0.05). It has been established that indicators of protein metabolism in ROLO have age-related features. Thus, six-year-old hybrids have a higher level of whey protein content (39.3±1.34 g/l) and AST activity (4.71±0.11 µkat/l), but a lower level of ALT activity (1.67±0.18 µkat/l), compared with three-year-olds, in which the average values of these indicators were, respectively, 31.84±0.92 g/l, 3.05±0.39 and 2.58±0.16 mkat/l. Age differences were also found in the study of lipid metabolism. In the group of six-year-olds, the cholesterol content was lower than in three-year-olds (1.67±0.11 and 2.05±0.1 mmol/l, respectively) (p > 0.05). But the content of serum triglycerides did not differ significantly, only a tendency to a higher level of this indicator in six-year-olds compared to three-year-olds was noted (3.07±0.14 and 2.28±0.11 mmol/l, respectively). When studying carbohydrate metabolism, a higher level of glycemia was found in the group of six-year-olds compared to three-year-olds: 2.52±0.16 and 1.68±0.15 mmol/l, respectively (p > 0.05). The pronounced variability of the glycemia index in both groups is characteristic — the coefficient of variation was at the level of 25.3–33.6%. The established parameters of variation and age specificity of indicators of the erythron system, protein, lipid and carbohydrate metabolism can be used in assessing the state of physiological adaptation of the ROLO hybrid at the end of the growing period in cages in the Volga delta.