Nutrition plays a critical role in enhancing growth performance, health, an‎d cost-efficiency in aquaculture. One effective approach to reducing feed costs is the partial replacement of expensive protein sources with affordable energy sources such as carbohydrates. Maltodextrin, a highly digestible carbohydrate with good bioavailability, is considered a promising energy source for carnivorous fish like rainbow trout (Oncorhynchus mykiss). This study aimed to eva‎luate the effects of dietary maltodextrin at different levels (0%, 5%, 10%, an‎d 20%) on growth performance, blood biochemical indices, body composition, an‎d immune response in rainbow trout. A total of 144 rainbow trout with an average initial weight of 21.06 ± 0.88 g were ran‎domly divided into four dietary treatments with two replicates each an‎d fed for 45 days. Growth parameters such as weight gain, specific growth rate (SGR), feed conversion ratio (FCR), an‎d feed efficiency (FE) were measured. Blood biochemical parameters (glucose, cholesterol, triglycerides, total protein, albumin, liver enzymes) an‎d hematological indices (lymphocytes, monocytes, neutrophils, basophils, eosinophils) were also analyzed. The results showed that 10% maltodextrin in the diet significantly improved growth, reduced FCR, an‎d enhanced protein an‎d energy utilization. Blood an‎d immune parameters were within normal ranges, with improved liver health an‎d reduced internal fat. In contrast, the 20% maltodextrin group showed signs of liver fat accumulation, elevated liver enzymes, an‎d potential metabolic stress, although survival remained 100% in all treatments. In conclusion, dietary inclusion of 10% maltodextrin can effectively support growth performance, metabolic balance, an‎d immune health in rainbow trout without adverse effects. Therefore, maltodextrin at this level may serve as a cost-effective an‎d nutritionally beneficial energy source in aquafeed formulations.

عيسي ابراهيمي درچه

اميدوار فرهاديان , محمدرضا دهقاني

يزدان كيواني , اميد بيرقدار كشكولي