Study On Compensatory Growth In Carassius Auratus

This study is about the compensatory growth of goldfish(average initial body weight 36.7275±3.08g)under 18±2℃after starvation and refeeding for different days. The changes of phological traits, the body component, the digestive enzyme activity and histology have been studied in goldfish; from which the countermeasure and mechanism of compensatory growth have been discussed. The result is as follows:After starvation, the body weight, length, hepatosomalic index, condition factor and specific growth rate in the experimental group decrease. The body weight and specific growth rate are sensitive to starvation while the body length, hepatosomalic index and condition factor is not. After refeeding, the body character is no significant difference compared with control group. In the period of refeeding, the growth speed of starvation group all exceeds the control group. The change of feeding rate is not obvious but the food conversion efficiency is high.After starvation, the content of moisture of goldfish ascends and the content of liver glycogen, muscle glycogen and content of fats descends, while the content of protein and ash doesn't change. After refeeding, the body component is no significant difference except for content of fats compared with control group. The results indicate that glycogen is used first and then it is the fat in hunger, finally may be protein. Goldfish use fat as energy sources, the lost part is replaced by moisture. Goldfish first accumulates the glycogen when it stores the energy material,then is fat.After starvation, the activities of protease, trypsin and lipase of digestive tract in goldfish all decrease, whatmore after refeeding, the activities ascends. At the end of the experiment, the enzyme activities is significant difference compared with control group, except protease in intestines is higher than the control group. After starvation, the activities of amylase ascends. The activities of amylase is always higher than the control group after refeeding until the end of the experiment. The distribution orderliness of different digestive enzymes activities in the digestive tract is:protease and trypsin activities in intestines is higher than the activitie in hepatopancreas; Amylase activity in hepatopancreas is higher than the activitie in intestines; Lipase activity in hepatopancreas is same with the activitie in intestines.Intestines and hepatopancreas of goldfish after starvation for 7d is the same to the control group, while the fish after starvation for 14d and 21d change obviously: hepatocyte is irregular and diminishes, and intercellular space appears, cell boundary dims, the nucleus shift from one side of the cell to the center, the height of intestinal villus and epithelium descends. Microvilli of the intestinal epithelium is irregular. After refeeding,most primary structure resumes, some of the factors reurn to previous levels but most factors not.During starvation and refeeding of goldfish, the body weight and specific growth rate are sensitive to starvation while the body length, hepatosomatic index and condition factor is not sensitive to starvation. It could be seen from the change of body weight and specific growth rate that goldfish shows completely compensatory growth, It could be seen from the change of food conversion efficiency and feeding rate that the completely compensation growth mainly due to the increased food conversion efficiency. Starvation could be used in breeding process of goldfish appropriately and moderately. It is important to feeding goldfish by scientific using of this physiological phenomenon.