Effects of different dietary canola and fish oil levels on overall performance, fatty acid profile, haemato‐biochemical responses, and digestibility of macronutrients of Caspian brown trout ( Salmo trutta caspius Kessler) fingerling

Abstract

A 2-month feeding trial was undertaken to evaluate the effects of replacing dietary fish oil (FO) with canola oil (CO) at four levels of HF (100% fish oil), FF (70% fish oil + 30% canola oil), FV (50% fish oil + 50% canola oil), and HV (100% canola oil) on overall performance, haemato-biochemical responses, fatty acid composition and digestibility of Caspian brown trout, Salmo trutta caspius (Kessler) fingerlings. Fingerlings (N = 180, 4.6 ± 0.23 g) were randomly scattered to four various diet treatments. In fingerlings fed with FV diet a considerable increase in specific growth rate and weight gain were recorded (p < .05). No significant difference was observed in none of the macronutrients of the whole-body among the treatments (p > .05). The highest saturated fatty acids and the lowest monounsaturated fatty acids were recognized in the HF diet (p < .05). The lowest red blood cell was found in fingerlings fed HF diet (p < .05), but the white blood cell activity was not influenced in the groups (p > .05). The fingerlings that consumed the HF diet implied the highest aspartate transaminase, alanine transaminase, alkaline phosphatase and lactate dehydrogenase activities in serum than the other groups (p < .05). None of the whole-body compositions such as protein, lipid, ash, and moisture were affected by dietary treatments (p > .05). The lowest value of apparent digestibility of crude lipid (ADCCL) was observed in the HF group (p > .05). Overall, the data exhibited that elevating dietary canola oil up to 50% in Caspian brown trout fingerling resulted to improve growth efficiency and blood biochemistry.