Effects Of Starvation (fasting) And Refeeding On The Body Parameters And Hepatocyte Ultrastructure In Three Fish Which Live In Different Salinity Water

This paper shows the effects of starvation or fasting (4 weeks) and refeeding (8 weeks) on the body parameters (norm length, entire length, body width, body height, the body weight, the liver weight, condition factor .hepatosomatic index and SGR) and the hepatic ultrastructure in three fish which live in different salinity water [Channa maculata, Rhabdosargus globiceps(Cuvier), Sarotherodon aurea (Steindachner)}. In the meantime, the compensatory mechanism of these fish was discussed.The body parameters of fish changed when fish was subjected to starvation or fasting. In this case, Channa maculata showed the significant reduction of the body height, the liver weight, the condition factor, the hepatosomatic index and SGR; Rhabdosargus globiceps showed the significant drop of the liver weight, the condition factor and the hepatosomatic index; Sarotherodon aurea showed the significant fall of the norm length, the entire length, the body width, the body weight ,the liver weight, the condition factor, the heapatosomatic index and SGR. After refeeding, the norm length, the entire length, the body weight, the starvation group's body height, the body width and hepatosomatic as well as the fasting group's SGR in Channa maculata were recovered completely; but the starvation group's SGR had a significant descend. All body parameters of Rhabdosargus globiceps were recovered after 8 weeks's refeeding . In Sarotherodon aurea's part , all parameters except the body height, SGRi the fasting group's condition factor and the starvation group's hepatosomatic index all were lower significantly than the control.There are some changes of hepatic ultrastructure when fish is subjected to starvation and are refed. Firstly, starvation lead to the fish adapting their hepatic ultrastructure: the total number of cell organelles, the number of rough endoplasmic reticulum , lipid-drops decrease ; the mitochondria appears many forms and its two membranes separate. After refeeding, the quantity of cell organelle, rough endoplasmic reticulum , lipid-drops increase; Golg body is found hi Sarotherodon aurea; dark cells are found in Channa maculata. These phenomena demonstrate that the types, the quantities and the form of cell organelles are closely related to the hepatocyte metabolism.As far as the type of the compensatory growth is concerned* Channa maculata and Rhabdosargus globicep belong to completely compensatory growth because the body weight of the two disposition groups of the two fish recovered completely. Sarotherodon aurea only have partially compensatory growth because its two disposition groups'body weight cannot catch up with the control in the refeeding'sand its SGR in the stage of refeeding is equal to the control generally.The principle of compensatory growth is as fellow: high ration level in Channa macvlata and Sarotherodon aurea ; high ration level and high conversion efficiency of forage in Rhabdosargus globicep .Li the refeeding stage of this experiment, the three fish all show the high conversion efficiency, especially in Rhabdosargus globicep. In the meantime, this test was proceeded in outdoors in which the environment is close to the natural condition. So, this experiment is practical in some degree.