Study On Compensatory Growth In Oncorhynchus Mykiss Juvenile

This study is about the compensatory growth of kingtrout juvenile (average initial body weight 31.52±1.33g) under 16±2℃after starvation and refeeding for different days. The changes of character, the body component , the physiological and biochemical index of blood and the digestion enzyme activity have been studied in kingtrout juvenile. Countermeasure and mechanism of compensatory growth have been discussed. The result is as follows:After starvation, the body weight, length , hepatosomalic index , corldition factor and specific growth rate in the experimental group decrease. The body weight, hepatosomalic index , corldition factor and specific growth rate are sensitive to starvation while the body length is not sensitive to starvation. After refeeding, the body character is no significant difference except for body weight 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 and that of food conversion efficiency is very obvious.After starvation, the content of moisture and ash of kingtrout juvenile ascends while the content of muscle glycogen and liver glycogen descends. After refeeding, the body component is no significant difference except for muscle glycogen compared with control group. The results indicate that the liver is the main organ stores energy of kingtrout juvenile and the fish can use glycogen as energy sources; What first uses is the glycogen and then it is the fat in hunger; The fish first uses the liver glycogen and then the muscle glycogen in hungry; Kingtrout juvenile first accumulates the liver glycogen when it stores the energy material.After starvation, red blood cell count , hemoglobin , hematocrit and erythrocyte sedimentation rate of kingtrout juvenile levels decline significantly while white blood cell count shows a downward trend; after refeeding, the physiological index of the blood returned to the level with no significant difference compared with control group. After starvation, the glucose level of blood declines significantly and it declines faster in the early period of starvation while later it maintains a certain level. Total cholesterol o and triglyceride levels are similar sawtooth-shaped ladder decline The total protein content of the blood did not change significantly. After refeeding, the biochemical index of the blood returned to the level with no significant difference compared with control group.After starvation, the activities of protease , trypsin and alanine aminotransferase of digestive tract in kingtrout juvenile all decrease. And they all fall faster in the early period then later fall slower. Lipase activity decreased after the first of increased while amylase activity first increased and then decreased. After refeeding, the activities of amylase and lipase are on the rise compared to before, but amylase activity on the whole is still below the same period in the control group while lipase activity is higher compared with control group . The activities of protease , trypsin and alanine aminotransferase return to the level with no significant difference compared with control group. They basically have not changed, and have remained stable condition. The distribution orderliness of different digestive enzymes activities in the digestive tract is: protease and trypsin activities are highest in stomach and pyloric, secondly in intestines ,thirdly in hepatopancreas. Amylase activity is highest in intestines, secondly in pyloric, thirdly in stomach , fourthly in hepatopancreas. Lipase activity is highest in intestines, secondly in stomach and pyloric , thirdly in hepatopancreas.It could be seen from the change of body weight and specific growth rate that kingtrout juvenile shows partially compensatory growth. It could be seen from the change of food conversion efficiency and feeding rate that the partially compensation growth is mainly due to increased food conversion efficiency. Starvation should be avoided or reduced in breeding process of kingtrout . It has important significance to feeding kingtrout by scientific using of this physiological phenomenon.