Dietary essential oil extract from sweet orange (Citrus sinensis) and bitter lemon (Citrus limon) peels improved Nile tilapia performance and health status

Abstract

The effects of dietary essential oils extract from sweet orange (Citrus sinensis) (OEO) and/or lemon (Citrus limon) (LEO) peels on performance and health status of Nile tilapia were investigated. Seven triplicate groups (Control "CG", OEO1‰, OEO3‰, LEO0.75‰, LEO1‰, OEO1‰ × LEO0.75‰ and OEO3‰ × LEO1‰) of fish (16.42 ± 0.059 g, N = 210) were fed basal diet, basal diet contain OEO 1‰, OEO 3‰, LEO 0.75‰, LEO 1‰, OEO 1‰ × LEO 0.75‰ and OEO 3‰ × LEO1‰ respectively, for 60 day. Results showed significant improvement in growth (final weight, weight gain, specific growth rate and thermal growth coefficient), blood health (increased total protein, albumin, globulin and decreased aspartate aminotransferase, alanine aminotransferase, cholesterol, triglycerides and glucose), immune response (phagocytic activity, phagocytic index and lysozyme activity) and oxidative status (super oxide dismutase and catalase) of fish received OEO or/and LEO in respect to CG (p < 0.05) with the best findings observed in OEO 3‰ × LEO1‰. In a dose-dependent effect, liver insulin growth factor I (IGF-I), super oxide dismutase (SOD) and tumour necrosis factor-alpha (TNF-α) significantly upregulated in fish received OEO or/and LEO compared with CG (p < 0.05). Dietary supplementation of OEO or/and LEO significantly improved the intestinal morphometry (villi length, inter villi space and number of goblet cells) of fish compared to CG (p < 0.05) with the best results detected in OEO 3‰ × LEO1‰. Conclusively, OEO 3‰ × LEO1‰ have significant physiological, antioxidant and immunostimulant activities that could be used as natural constituents during the formulation of aquafeeds to improve fish welfare via dietary management.