PHYSIOLOGICAL DYNAMICS OF SHORT-TERM STARVATION IN MANDARIN FISH (SINIPERCA CHUATSI) AT LOW WATER TEMPERATURE

In order to study the physiological dynamic change process of hungry mandarin fish under low water temperature, 270 mandarin fish with body weight of (84.13±0.14) g were selected and randomly divided into 6 groups with 3 replicates in each group and 15 fish in each replicate. The fish were starved for 0, 3d, 6d, 9d, 12d and 15d at low water temperature of (13±1)℃. The relevant physiological and biochemical indexes were measured every three days. The results showed as follows: (1) With the extension of hunger time, the body weight, fullness, ratio of liver to body, ratio of viscera to body, protein and fat content of muscle of mandarin fish decreased gradually. The body weight decreased by a larger margin with a reduction of 3.03%, 3.82%, 5.55%, 7.68% and 8.39% after 3d, 6d, 9d, 12d and 15d of starvation, respectively. (2) The activities of alanine aminotransferase and asoxal aminotransferase in the blood of mandarin fish decreased first and then increased with the extension of starvation time, reaching the minimum value on the third day. Blood glucose content increased significantly on the 6th day of starvation (P<0.05), and then remained in a certain range. Alkaline phosphatase activity, triglyceride, total cholesterol and high density lipoprotein cholesterol contents showed an overall decreasing trend. (3) The activities of pepsin, H⁺-K⁺-ATPase in stomach, trypsin and lipase in intestinal tract and pyloric blind cyst of mandarin fish showed an overall decreasing trend with the extension of starvation time, and all reached the minimum value on the 15th day of starvation, among which the decrease of H⁺-K⁺-ATPase activity in stomach was the most significant. The activity of amylase was stable in early starvation period and decreased in late starvation period. (4) The antioxidant capacity of the liver of mandarin fish first increased and then decreased with the extension of starvation time, and reached the lowest value on the 15th day. The results indicate that the short-term starvation of mandarin fish shows negative growth of body mass, slimming of body size and relatively smaller of liver under low water temperature. During the first 3d of starvation, muscle fat was preferentially used for energy, and muscle protein was preferentially used for energy in the later period. On the sixth day of starvation, the antioxidant capacity of the liver of the mandarin fish was improved, but the digestive and antioxidant function of the mandarin fish decreased significantly after prolonged starvation, and the feed inhibited the secretion of gastric acid, which may be related to the protection of gastric mucosa.