Research On The Effects Of Heat Stress On Jifu Tilapia

The study aimed at studying high temperature stress on the impact of the JiFu tilapia.By curvilinear regression analysis for experiment data, UILT50of high temperature stress on JiFu tilapia was37.67℃,the rising rate suitable for the study was0.5℃/h. Intestinal digestive enzyme activity,antioxidation competence in liver and immune function of JiFu tilapia under high temperature stress at different time point (Oh,12h,24h,48h,7d) were investigated.The changes of growth performance,intestinal digestive enzyme activity,antioxidation competence in liver and immune function of JiFu tilapia at28℃,34℃,36℃and38℃were observed respectivelyThe results showed that the activity of pepsin, lipase and amylase were presenting increasing due to the increase of stress time in period of0h-24h. The values of pepsin, lipase and amylase were decresed due to the increase of stress time in period of24h-7d.Slight oxidative damage occurred on liver of JiFu tilapia in period of0h-24h. In period of24h-7d,the antioxidant capacity of liver elevated against oxidative damage caused by high temperature stress.Immune function of JiFu tilapia significantly declined after7d stress.The results showed, AGR (Absolute Growth Rate) was lower and FCR (Feed Conversion Rate)was higher at a higher temperature. When water temperature reached34℃,the activity of the digestive enzymes was highest.When water temperature was higher than36℃,heat stress led to liver oxidative damage of JiFu tilapia. After24h under different temperature of high temperature stress,the immune function of JiFu tilapia have no change. The findings indicated that the digestive system, immune system and antioxidant capacity of JiFu tilapia under the high temperature stress are more sensitive to time factor. High temperature stress last for less than24h did not cause changes in physiological function and physical injury of JiFu tilapia.