The change in activity of digestive enzymes of Penaeus monodon at different growth stages

The change in activity of protease,lipase and amylase of Penaeus monodon at different growth stages was analysed in this paper,and the digestibility and availability of pro- tein,lipid and carbohydrate during these periods were studied.The results showed that the growth of P.monodon can be divided into two stages based on the activity of digestive enzymes. The first growth stage was at body lengths of 10～12.5 cm,when the activity of protease and li- pase continued rising with the increase in size of the shrimp.The second growth stage was at body lengths greater than 12.5 cm,when the activity of protease and lipase declined to some ex- tent.The activity of protease,lipase and amylase in three digestive organs(hepatopancreas, stomach,intestines)were different at different growth stages.The ranking of protease activity in these organs was hepatopancreasstomachintestines;the ranking of lipase activity was in- testyhepatopancreasstomach;and the ranking of amylase activity was intestinesstomachhepatopancreas.