Studies On The Histology And Enzyme In Larva-juvenile Digestive System Of Epinephelus Malabaricus (Bloch&Schneider)

Epinephelus malabaricus Bloch&Schneider is the precious culturing marine fish, E. malabaricus has a higher degree of difficulty to artificial breeding and the survival rate is low. This paper systematically studied the histology, mucous cells and digestive enzymes of digestive system. Reveals the characteristics of development and digestion capacity variation of the digestive system. Designed to properly adjust the feeding strategies in the process of artificial breeding, to give the larva-juvenile with adequate nutrition and to improve seedling survival and growth rates provide a theoretical basis.A serial paraffin slice method was used to observe the digestive system in E. malabaricus during its post-embryonic development which divied into14groups (0-42days) with optic microscope. Describe the digestive system histology structural features and the law of genesis and development. The results showed that:Under the conditions of the water temperature from24to28℃, the prototype of liver and pancreas appeared when2DAH of E. malabaricus. In3DAH when the yolk sac is gradually reduced, the mouth and the anus were interconnected, the oropharyngeal cavity and the esophagus were interconnectde at the same time, brush border appeared in the intestine from3DAH to4DAH.The digestive system has obviously differentiated into the esophagus, stomach and intestines and liver and pancreas in the4DAH. And the fish change its endogenous feeding into exogenous feeding nutrition, which shows that the change of digestive system is adapt to predatory change.Taste buds appeared at oropharyngeal cavity and mucous cells appeared at esophagus and intestinal in5DAH. Mucous cells appeared at stomach in7DAH. Gastric gland appeared in35DAH. The pyloric caecum appeared at pylorus of the stomach in42DAH, during the following growth of the fish, function and structure of the digestive system was becoming mature and perfect gradually.Measuring activities of digestive enzymes changes from0DAH to28DAH of larval-juvenile of E. malabaricus by using enzyme technology methods, The major obtained results were as follows:Rapid decline in protease activity from the larvae began to feed and has maintained a low level to pre-abnormal, after gastric gland appears, acid protease and neutral protease activity increased rapidly, alkaline protease activity is more stable. Higher amylase activity after hatching, then the activity wavy changes, and finally with the development of amylase activity gradually stabilized at a low level. Lipase has a strong activity from the larvae began to feed, and Enzyme activity decreased with the yolk sac narrowing. A greater change in acid phosphatase and alkaline phosphatase activity.