Dynamic changes of growth, digestion, metabolism, antioxidant and immune ability of Siniperca chuatsi during overwintering period

In order to investigate the physiological dynamic changes in growth, digestion, metabolism, antioxidant, and immune ability of Siniperca chuatsi during the overwintering period, 240 S. chuatsi with a body weight of (107.63±0.48) g were selected and divided into growth and sampling groups with four replicates per group and 30 fish per replicate. Feed once every two days for 112 days. During this period, the water temperature experienced a cooling period of 14.5–7.5 °C (0–6 weeks) and a warming period of 7.5–14.5 °C (6–16 weeks). Seven sampling points were set at 0 (0-week), 2 weeks (2-week), 4 weeks (4-week), 6 weeks (6-week), 8 weeks (8-week), 12 weeks (12-week), and 16 weeks (16-week). The results showed that the weight gain rate (WGR), specific growth rate (SGR) and feeding rate (FR) decreased gradually and then increased gradually after reaching their lowest values at 6-week. The feed coefficient increased significantly at 6-week and then decreased. The activity of the gastric proton pump (H⁺-K⁺-ATPase), intestinal trypsin, and amylase increased after a decrease of 6-week. The liver total antioxidant capacity and superoxide dismutase activity decreased significantly at 6-week, while malondialdehyde content increased significantly. The plasma acid phosphatase activity, immunoglobulin content, and spleen immunoglobulin content decreased significantly and then increased. At 8-week, the liver structure begins to show partial nuclear migration to the periphery of hepatocytes and vacuolar degeneration. At 16-week, the S. chuatsi liver cells had an irregular morphology and disappeared or even dissolved nuclei. The intestinal villi at 8-week were lower, sparser, and irregular than those at 0-week, and the development of intestinal villi at 16-week was better than that at 0-week and 8-week. In conclusion, the digestive, antioxidant, and immune abilities of S. siniperca in the early overwintering period were weakened, the body weight of S. siniperca in the late overwintering period was significantly increased, and liver structure and function were seriously damaged. This study provides a theoretical basis for the management of S. chuatsi feeding and breeding during overwintering period, and promotes the high-quality development of the S. chuatsi farming industry.