Dietary coriander (Coriandrum sativum L) oil improves growth, nutrient utilization, antioxidant status, tissue histomorphology and reduces omega-3 fatty acid production in Nile tilapia (Oreochromis niloticus)

Abstract

Coriander (Coriandrum sativum L.) is recently emerging as an antimicrobial growth promoter in aquafeed formulations. To assess the effect of coriander seed oil in the feed of Nile tilapia five iso-nitrogenous (crude protein 40%) and iso-lipidic (crude lipid 7%) diets were prepared with graded levels of coriander oil i. e., 0, 5, 10, 15 and 20 g/Kg referred as C0, C5, C10, C15 and C20, respectively. The fish were fed with the experimental diets twice daily for a period of 60 days in triplicate. After the feeding experiment, there observed a linear pattern in weight gain with the dietary coriander oil levels. The expression of hepatic insulin like growth factor 1 gene increased significantly in coriander oil supplemented groups in dose dependent manner in hepatic tissues of tilapia. The viscerosomatic and hepatosomatic index decreased significantly in the coriander oil treated groups. The crude protein contents increased significantly in the experimental groups; however, it did not vary significantly in between the groups. The crude lipid contents increased significantly in the last three groups (C10, C15 and C20) compared to C0 and C5. The serum glucose content decreased significantly in the last three groups i.e., C10, C15 and C20 coriander fed groups compared to C0. Whereas, the HDL level increased significantly in the 20 g/Kg treatment group compared to rest of the groups. Catalase activity increased significantly in the liver tissue of coriander oil treated groups compared to control. The liver histomorphology showed signs of storage of carbohydrate or lipid reserves in the form of vacuoles in the control group. However, in the coriander supplemented groups there was a reduction in hepatic vacuolar structures. The appearance of intestinal villi was enriched in coriander oil supplemented groups via branching. The Δ6/Δ5 desaturase increased significantly in the experimental groups compared to control. The Δ4 desaturase and elongase decreased significantly beyond 6.3% and 11.7% of coriander oil in the diet, respectively. There observed a significant increase in the percentage of saturated fatty acids in dose dependent manner. However, the unsaturated fatty acids including omega-3 fatty acids decreased significantly with an increase dose of coriander oil in feed of Nile tilapia. It can be concluded from the above study that coriander essential oil can be used for better growth performance, intestinal nutrient absorption, antioxidant activity and decreasing hyperglycemia in Nile tilapia. However, higher inclusion level (above 5 g/Kg) led to decrease in the wholebody omega-3 fatty acid production.