Effects of Low Temperature Stress on Digestive Enzyme Activity in Tilapia

The effects of water temperature at 12℃,15℃,20℃and 25 ℃respectively on the digestive enzymes activity of tilapia were studied.The results showed that Egyptian strains of Nile tilapia,the activity of amylase in anterior intestion and posterior intestine,hepatic lipase and activities of lapse reduced significantly when the water temperature reduced from 25℃to 20℃,15℃and 12℃,and the activities of protease in anterior intestine reduced significantly at 12℃compared with the temperature of 15℃,20℃and 25℃(P0.05),In American strains of Nile tilapia,the activities of protease in anterior intestine and activities of amylase in posterior intestine reduced significantly(P0.05),and the activities of amylase,hepatic lipase and amylase of lapse in anterior intestine reduced significantly in 12 ℃.In American strains of Oreochromis aureus,the activities of amylase,hepatic lipase and activities of lapse in anterior intestine reduced significantly,and the activities of protease in anterior intestine and activities of amylase in posterior intestine reduced significantly at 12 ℃ and 15 ℃(P0.05).When the water temperature was between 12℃to 25℃,the activities of amylase and protease in intestine reduced with the decrease of the temperature with the lowest at 12℃.The activity of hepatic lipase was the lowest in Egyptian strains of Nile tilapia at 20℃,in American strains of Nile tilapia at 12℃,in American strains of Oreochromis aureus at 20℃.