Supplementation of diets for Oreochromis niloticus with essential oil extracts from lemongrass (Cymbopogon citratus) and geranium (Pelargonium graveolens) and effects on growth, intestinal microbiota, antioxidant and immune activities

This study aimed to investigate the effects of dietary supplementation of lemongrass (Cymbopogon citratus) (LEO) and geranium (Pelargonium graveolens) (GEO) essential oils on growth, immunity, antioxidant responses and disease resistance of Oreochromis niloticus. Fish (3.04 +/- 0.003 g) were fed the basal diet (G(1)), or the basal diet supplemented with LEO at 200 and 400 mg kg(-1) of the diet (G(2) and G(3)), or GEO at 200 and 400 mg kg(-1) of the diet (G(4) and G(5)), respectively for 12 weeks. Growth indices and feed utilization were significantly improved with G(2), G(3) and G(5) groups. Also, a significant increase in protein content of the whole body was recorded in all groups. G(2) and G(5) showed a significant rise of both catalase activity and reduced glutathione content with a significant incline in the MDA level. Lysozyme activity and total IgM levels were significantly increased in G(2) and G(5) groups. G(3) and G(5) groups had a significantly lower intestinal total bacteria, Coliforms, Escherichia coli and Aeromonas spp counts. Following challenge with A. hydrophila, all groups had a high survival rate. In conclusion, LEO and GEO could be a candidate dietary supplementation in fish improving growth performance, feed utilization, oxidative status, immune responses and disease resistance.