Comparison of physiological status of short-term starvation and feeding of mandarin fish (Siniperca chuatsi) at low temperature in winter

In this experiment, a comparative study of the physiological states of short-term starvation and feeding of mandarin fish was carried out under the conditions of water temperature (13±1) °C with reference to the winter water temperature in Guangdong Province. Ninety mandarin fish with the initial body weight of (84.13±0.14) g were selected and randomly divided into starved group (starved 15 days) and feeding group (feeding 15 days). Physical and chemical indexes were measured after the trial. The results showed: ① the final body weight, liver glycogen, crude protein and crude lipid of the whole body and muscle in feeding group were significantly higher than those in starved group. The weight gain rate in feeding group was 7.54% while the weight loss rate in the starved group was 8.39%. ② The activities of alanine transaminase and aspartate transaminase in plasma of mandarin fish in feeding group were significantly lower than those in starved group, but the concentration of triglyceride was significantly higher than that in starved group and there was no significant difference between the number of various blood cells and glucose level. ③ The activity of digestive enzyme and the development of intestinal tissue structure in the feeding group were significantly higher and better than those in starved group. ④ Feeding group had a better antioxidant capacity than starved group, moreover, liver cell in starved group had an obvious structural damage and the number of lipid droplets in starved group was significantly lower than that in feeding group. ⑤ The activity of lysozyme in plasma and the content of IgM in plasma, spleen and kidney in feeding group were significantly higher than those in starved group. ⑥ There was no significant difference in amino acid composition of dorsal muscle of mandarin fish between feeding group and starved group. However, there were significant differences in the composition of fatty acids. The total saturated fatty acids and monounsaturated fatty acids in the dorsal muscle of mandarin fish in feeding group were significantly lower than those in starved group, while the total polyunsaturated fatty acids and high unsaturated fatty acids in feeding group were significantly higher than those in starved group. In conclusion, under this experimental conditions, the difference between the feeding group weight gain and starved group weight loss was 15.93%, in addition, in the starved group, the digestive and immune ability were decreased, the antioxidant ability of liver was weakened and the cellular structure was damaged while in the feeding group, the digestion, immunity and liver function of the mandarin fish were relatively normal. The contents of dorsal muscle protein and lipid were higher than those in starved group, and the composition of fatty acids was improved and the composition of amino acids was stable.