Effects of partial replacement of fish oil by vegetable oil and animal fat on hematological and serum biochemical parameters, antioxidant capacity, lipase activity and intestine histology of rainbow trout (Oncorhynchus mykiss)

Document Type : Original research

Authors

• Sepideh Alami
• Sarah Jorjani
• Afshin Ghelichi
• Zahra Ghiasvand

Department of Fisheries, Faculty of Agriculture Sciences and Natural Resources, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran

10.22034/iar.2023.1982365.1415

Abstract

The present study determined the effects of replacing fish oil (FO) with canola oil (CO) and/or beef tallow (BT) on various parameters of rainbow trout (Oncorhynchus mykiss). For this aim, 250 fish (20 g) were selected and randomly assigned to different groups: T1 or control (100% FO), T2 (50% FO and 50% BT), T3 (50% FO and 50% CO) and T4 (50% FO, 25% BT and 25% CO). The highest mean final weight, weight gain and survival rate belonged to T1 and T4 while the lowest rates were seen in T2 (p<0.05). Red blood cell (RBC), hemoglobin and hematocrit of the fish decreased significantly when FO in diet was replaced by CO or BT or a blend of them (p<0.05). Moreover, significant differences were detected in other blood parameters (p<0.05) except for monocytes, eosinophils, and immunoglobulin (Igm) (p>0.05). Also, there were significant differences in serum biochemical factors (p<0.05) except for lysozyme (p>0.05). Histologically, unlike T1, other samples showed signs of cellular damage. In conclusion, partial replacement of fish oil with an equal blend of CO and BT in rainbow trout diet is recommended.

Keywords

• Rainbow trout (Oncorhynchus mykiss)
• Fish oil
• Canola oil
• Beef tallow
• Growth parameters
• Intestine histology

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