Effect of crowding stress on growth performance, the antioxidant system and humoral immunity in hybrid sturgeon

Abstract

To evaluate effects of crowding stress on the physiological mechanisms of juvenile hybrid sturgeon (♀Acipenser baerii×♂Acipenser schrenckii, 23 ± 1 g body weight), an experiment was assigned to three initial stocking densities in flowing water ponds (LD = 100 and 150 fish/m3; MD = 200 and 250 fish/m3; and HD = 300 and 350 fish/m3) for 60 days. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to identify differential metabolites between different stocking densities. The final weight, weight gain rate (WGR) and specific growth rate (SGR) decreased significantly as the stocking density increased (P < 0.05). Gill filaments incurred injury in the MD and HD groups. Crowding stress increased significantly serum cortisol and glucose levels (P < 0.05), and inhibited the antioxidant capacity. However, stocking density did not affect innate immunity parameters in fish, including complement c3, immunoglobulin M (IgM) and lysozyme (LZM). These negative growth performances to crowding stress mainly involved pathways associated with ascorbate and aldarate metabolism, butanoate metabolism, and fatty acid degradation. The gluconeogenesis and glycogenolysis were activated by the glucagon signaling pathway in order to meet the increased energy expenditure of fish under stress, which played a protective role against lipid peroxidation. Assessment of these factors allows for a more comprehensive understanding of the underlying physiological mechanisms associated with crowding stress in hybrid sturgeon.