Influence of dietary nucleotides on growth performance and stress resistance in kutum (Rutilus kutum Kamenskii, ۱۹۰۱)

A feeding trial has been conducted to evaluate the effects of dietary nucleotide (NT) on growth performance and stress resistance of fry kutum (Rutilus kutum Kamenskii, ۱۹۰۱). A basal diet supplemented with ۰ (control), ۰.۳, ۰.۵ and ۰.۷ g NT kg-۱ have been formulated for four experimental diets. After ۸ weeks of feeding trial, growth parameters were evaluated and then fish has exposed to osmotic stress. To elucidate the underlying physiological mechanisms, cortisol, apoptosis and HSP۷۰ levels were measured at selected times of ۰, ۲ h, ۸ h and ۲۴ h after the osmotic shock. The results revealed dietary NT feed exerts a positive effect on the growth performance of kutum fries and fish fed with ۰.۷ g  NT kg-۱ had the highest final weight compared with other treatments (p<۰.۰۵). Results of HSP۷۰ showed that fish fed with NT had higher levels of HSP۷۰ expression. Also, the levels of HSP۷۰ at ۲ h increased significantly, ۳-۷-fold over baseline levels (۰ h) and then decreased significantly at ۲۴ h, however HSP۷۰ levels at ۲۴ h was ۱-۳-fold over baseline levels. Apoptosis and cortisol values were affected by dietary NT levels and all NT groups showed lower stress-induced apoptosis and cortisol elevation, compared to control group.

Keywords:

Heat shock protein , Apoptosis , Stress responses , Dietary nucleotide.