The protective effect of vitamin E and C supplements on reducing the effects of oxidized fish oil on growth, hematological and biochemical indices in rainbow trout fry (Oncorhynchus mykiss)

The present study aimed to evaluate the protective effect of vitamins E and C on reducing the effects of dietary oxidized fish oil on the growth, hematological and biochemical indices of rainbow trout fry. For this purpose, 240 fries with an average weight of 12.75±0.25 g were fed with 4 treatments including, treatment 1: a diet containing fresh fish oil, treatment 2: a diet with oxidized fish oil, treatment 3: a diet containing oxidized fish oil along with the low level of vitamin supplements (100 mg/kg vitamin E, 200 mg/kg vitamin C) and treatment 4: a diet with oxidized fish oil along with the high level of vitamin supplement (200 mg/kg vitamin E, 400 mg/kg vitamin C) for 60 days. At the end of the trial, the indices of specific growth rate (SGR), weight gain percentage (WG), and food conversion ratio (FCR) were calculated. Also, the hematological and serum biochemical parameters: cholesterol, triglyceride, high density lipoprotein (HDL), and low density lipoprotein (LDL) were measured. Based on the obtained results, the SGR and WG, were decreased in 2, 3 and 4 treatments and the FCR was increased (p<0.05). The white blood cells (WBC), red blood cells (RBC), hemoglobin (Hb), and hematocrit (Htc) levels were increased in 2, 3, and 4 treatments (p<0.05). The triglyceride and HDL contents were increased in 3 and 4 treatments, respectively (p<0.05). Also, there were not significant differences between different treatments for serum cholesterol and LDL indices (p>0.05). Finally, it was concluded that oxidized fish oil has adverse effects on growth, hematological and biochemical indices, and the vitamin supplements are effective in reducing these effects on the hematological and biochemical parameters.