Effects of different dietary lipid sources on growth performance, salinity tolerance, haematological and biochemical parameters of Caspian Roach (Rutilus rutilus caspicus) juvenile

This study investigates the effects of replacement of fish oil by two vegetable oils (Sunflower oil and Soybean oil) on growth performance، salinity tolerance، hematological and serum biochemical profile of Rutilus rutilus caspicus over 56 days. Five diets were supplemented with 8% of either fish oil (FO) (control)، sunflower oil (SFO)، and soybean oil (SO) or a combination of 4% FO with 4% SFO and 4% FO with 4% SO، respectively. Triplicate groups of fish (24 fish per tank with an average body weight، of 5. 52 g) were assigned to each diet. Blood samples were taken from the caudal vein of 75 apparently healthy fish at the end of trial. Hematological values of the blood samples were determined using standard techniques. At the end of experiment fish were exposed to salinity stress. The results showed that the best growth performance was in fish fed control diet، but this results were similar to B، C and D groups (P>0. 05). Serum cholesterol and glucose concentrations were significantly higher in fish fed diet containing vegetable oils (P<0. 05). Also the count of red blood cells (RBC)، hematocrit (Ht) and hemoglobin (Hb) in groups fed diet containing SFO and SO were higher than other groups (P<0. 05). There was no significant difference in survival index after 48 hours salinity stress (P>0. 05). These results indicate that fish oil can be replaced completely with alternative vegetable lipids without any serious negative growth performance and health impacts.