Herbal essential oils improve growth, antioxidant response, and gene expression in Nile Tilapia fingerlings

Abstract

The 30 and 60 mL/kg groups showed significantly improved final body weight, weight gain, specific growth rate, and feed conversion ratio (<i>p</i> < 0.05). Hematological parameters increased, while serum cholesterol and triglyceride levels decreased. Enhanced lysozyme activity, phagocytic rate, IgM concentration, and antioxidant enzymes (SOD and CAT) were observed in the 30 and 60 mL/kg groups. Additionally, these doses significantly upregulated the expression of growth- and immunity-related genes (GHr, IGF-I, IL-1β, TNF-<i>α</i>, ZO-1, and occludin) while downregulating HSP70, indicating improved stress resilience. Histological analysis revealed increased villi height and surface area in the intestine, suggesting better nutrient absorption. These findings demonstrate that dietary supplementation with 30-60 mL/kg of HEOs can enhance physiological and immunological health, offering a natural strategy to improve Nile tilapia aquaculture productivity.