Comparisons Of The Digestive Enzyme Activities Between Wild And Cultivated Lateolabrax Japonicus And Effects Of Alkalinity On The Digestive Enzyme Activities Of Lateolabrax Japonicus Juveniles

The digestive enzymes of wild and cultivated Lateolabrax japonicus have been studied comparatively in different temperature and pH .The character and distributing of digestive enzymes have been discussed too.The experiment also studied Lateolabrax japonicus juvenile,s growth,digestion and feeding when the alkalinity changed abruptly from 1.47mmol/L of freshwater to 5,10,20 and 30mmol/L;The changes of character, glycogen and the digestive enzyme activity have been studied .Mechanism of alkalinity menace have been discussed also.The digestive enzyme distribution and the optimum temperature and pH in wild Lateolabrax japonicus is similar with cultivated Lateolabrax japonicus.For the amylase in Lateolabrax japonicus,the optimum pH were 6.0,7.0,6.0,5.0 in liver,intestine, pyloric caecum and stomach respectively and the optimum temperatures in all tissues was 33℃. For protease in Lateolabrax japonicus, the optimum pH were 7.0,8.0,7.0,2.0 in liver,intestine, pyloric caecum and stomach respectively and the optimum temperatures of protease in stomach were 41℃and in other tissues was 49℃.The distribution of protease and amylase activities in two groups showed the same regularity.The activities of amylase and protease were from high to low: intestine >pyloric caecum >stomach> liver.The activities of protease in intestine and pyloric caecum were obviously higher than stomach and liver. The activities of amylase in intestine and pyloric caecum were relatively higher than liver in cultivated Lateolabrax japonicus,but the differences in wild Lateolabrax japonicus were not clear.The activities of amylase in intestine and pyloric caecum in wild Lateolabrax japonicus is significantly lower than cultivated Lateolabrax japonicus under the optimum temperature and pH,yet, the activities of protease in stomach.Comparatively the activities of protease in intestine and pyloric caecum in wild Lateolabrax japonicus is obviously higher than cultivated Lateolabrax japonicus. These testified that different feeding determined different digestive enzymes activities in different tissues. While pH is 10,the increase of intestine amylase activities in cultivated type,not wild type, also indicated the different structure in two groups attributed to different feeding.The stomach protease amylase and pyloric caecum protease is more sensitive to temperatures hinted us adjust feeding content based on seasons and temperatures to rise food conversion efficiency.The alkalinity experiment show that the character, glycogen and digestion enzyme activity is no significant difference with control group at the alkalinity of 4mmol/L,but the body weight,feeding rate,food conversion efficiency and glycogen went down obviously and that of digestion enzyme activity is very obvious at the alkalinity of 10,20 and 30mmol/L. These denoted that the alkslinity over 10mmol/L will make against gowth, digestion and feeding of Lateolabrax japonicus.The body weight is sensitive to alkalinity, yet the body length come down slightly.Indicated that Lateolabrax japonicus need more energy reserve to resist alkalinity menace.The liver glycogen is more sensitive than the muscle glycogen showed that Lateolabrax japonicus juvenile first uses the liver glycogen under alkalinity menace.At the alkalinity of 10mmol/L, all digestion enzyme activities is lower than control group,but only liver protease and intestine amylase come down distinctly inferred that Lateolabrax japonicus as a wild salinity fish have a strong tolerance to alkalinity.