Oregano (Origanum vulgare) extract as phytogenic feed additive: Enhancing growth, carcass, hepatic biochemical indices and immune response in Labeo rohita

In aquaculture, plant extracts offer a sustainable solution by reducing costs and environmental impact compared to conventional pharmaceuticals. This study explored the effect of oregano ( Oregano vulgare ) extract on growth, carcass composition, blood parameters, mineral profile, liver biochemical parameters and immune response in Labeo rohita . Fish (n = 15 fingerlings/ group in triplicate) were fed with various percentages of oregano extract including 0 (T 0 ; control; no extract), 0.5 (T 1 ), 1 (T 2 ), 1.5 (T 3 ), 2 (T 4 ), 2.5 (T 5 ) and 3 (T 6 ) kg −1 for 13-weeks. After the feeding trial, growth indices, including weight gain, protein efficiency ratio and specific growth rate were significantly improved ( P < 0.05) in the T 2 and T 3 groups and all other treatment groups. Moreover, protein retention in muscles was significantly highest in the T 2 and T 3 groups whereas fat deposition was lowest in these same groups. Furthermore, the addition of 1 % oregano extract to fish diets was found to enhance hematological parameters and mineral absorption throughout the body. The inclusion of 1 and 1.5 % oregano extract significantly ( P < 0.05) enhanced the activities of hepatic enzymes such as catalase, glutathione peroxidase, and superoxide dismutase. While malondialdehyde level was found to be the lowest in the T 2 group. In conclusion, incorporating up to 1–1.5 % oregano extract into the diets of L. rohita can significantly enhance overall performance.