Document Type: Research Paper
Department of Fisheries, Faculty of Animal Science and Fisheries, Sari University of Agriculture and Natural Resources, P.O. Box: 578, Sari 4818168984, Iran.
Faculty of Fisheries and Environmental Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49138-15739, Iran.
A feeding trial was conducted to evaluate the effects of dietary nucleotide (NT) on growth performance and stress resistance of fry kutum. A basal diet supplemented with 0 (control), 0.3, 0.5 and 0.7 g NT kg-1 to formulate four experimental diets. After 8 weeks of feeding trial, growth parameters were evaluated and then fish exposed to osmotic stress. To elucidate the underlying physiological mechanisms, cortisol, apoptosis and HSP70 levels were measured at selected times of 0, 2 h, 8 h and 24 h after the osmotic shock. Results shown dietary NT feed exerts a positive effect on the growth performance of kutum fries and fish fed with 0.7 g NT kg-1 had the highest final weight compared with other treatments (P<0.05). Results of HSP70 showed that fish fed with NT had higher levels of HSP70 expression. Also, the levels of HSP70 at 2 h increased significantly, 3-7-fold over baseline levels (0 h) and then decreased significantly at 24 h, however HSP70 levels at 24 h was 1-3-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.