Impact of Dietary Essential Oils Blend on Nile Tilapia (Oreochromis Niloticus) Performance, Serum Biochemical Indices, Antioxidant and Immune Response

This study was conducted to evaluate the effect of essential oils blend (EOB) on growth performances, serum biochemical parameters, antioxidant and immune response in Nile tilapia (Oreochromis niloticus). One hundred and eighty fish (10 ± 0.9 g per fish) were divided into three groups with three replicates of each in 9 plastic aquaria as follow: control; fed on basal diet, EOB I fed on basal diet containing 2g/kg IMMU PROTECTON containing carvacrol, thymol and cinnamaldehyde, and EOB II fed on basal diet containing 5g/kg IMMU PROTECTON for 90 days. The results indicated that the EOB I and EOB II groups showed significant improvement in final body weight by 34%, weight gain, weight gain %, specific growth rate and better feed conversion ratio by 20.95% compared to the control group. The dry matter and crude protein contents of fish body were significantly (P < 0.05) elevated in the EOB I and EOB II groups while the ash content was the lowest. Digestion coefficients of dry matter, crude protein, fat and ash were significantly (P < 0.05) higher in the EOB I and EOB II compared to the control group. Moreover, EOB I and EOB II groups showed significant (P < 0.05) increase in haematocrit, red blood cells, heterophils percent count and decrease in white blood cells count compared to the control. In-addition, EOB I and EOB II groups showed an increase in superoxide dismutase (SOD) by 7.40% and 15.43% respectively, total antioxidant capacity by about 9.5%, immunoglobulin M by 12.30 and 24.61 % respectivey and lysozyme activity ) by 12% and 25.50% respectively and tended to decrease malondialdehyde levels than control group. Phagocytic % and phagocytic index in EOB I and EOB II groups were slightly elevated compared to the control one. Moreover, the profit generated per kilogram of fish was significantly (P < 0.05) higher in fish fed the EOB I and EOB II with improvement in economic efficiency. The findings demonstrate that dietary supplementation with an essential oil blend at inclusion levels of 5 g/kg results in higher significant (P < 0.05) enhancement of growth performance, immunological status, antioxidant capacity, and economic efficiency of fish.