The effect of partial and full fish oil replacement with poultry fat on growth performance, hematological and serum biochemical parameters, antioxidant capacity, and intestine histology of rainbow trout (Oncorhynchus mykiss)

This study investigated the effect of replacing dietary fish oil (FO) with poultry fat (PF) on some growth and blood parameters of rainbow trout (Oncorhynchus mykiss) to find a suitable alternative to fish oil. For this aim, 600 rainbow trout juveniles weighing 50.72±2.13 g were purchased and after the adaptation period, 25 fish in each pond were released in a completely randomized design with 9 treatments and 3 replications. Five diets were considered for two months containing 100%, 75%, 50%, 25%, and 0% FO (D1, D2, D3, D4, and D5, respectively), where FO was replaced with PF. The treatments were CTL (D1), 25PF (D2), 25PFR (D2, then D1), 50PF (D3), 50PFR (D3, then D1), 75PF (D4), 75PFR (D4, then D1), 100PF (D5), and 100PFR (D5, then D1). FO replacement with PF had no significant influence on growth parameters. Hepatosomatic index (HSI) increased significantly in 75PF and 100PF (P0.05). Some hematological, e.g. red and white blood cell counts (RBC and WBC, respectively), and serum biological parameters, e.g. glucose, triglyceride, and albumin, changed significantly (P