Dietary lemongrass essential oil nanoemulsion enhances growth and mitigates heat stress-induced oxidative and inflammatory responses in growing rabbits.

This study investigated the effects of dietary lemongrass essential oil nanoemulsion (LEONE) on growth performance, feed efficiency, physiological responses, and overall health in heat-stressed New Zealand White rabbits. Eighty healthy male rabbits, aged five weeks, were randomly assigned to four groups (20 rabbits per group) and fed diets containing 0, 150, 300, or 600 mg LEONE/kg for eight consecutive weeks. Supplementation with LEONE at 300 mg/kg significantly improved average daily weight gain by 11.73%, dressing percentage by 11.59%, while concurrently reducing the feed conversion ratio by 10.81%, respiration rate by 1.82%, and rectal temperature by 6.25% compared to the control group. Regression analysis indicated that the optimal dietary dose for maximizing average daily gain and minimizing feed conversion ratio was approximately 450 mg/kg diet. Hematological profiles were enhanced, with increased red blood cell counts and decreased white blood cell counts following LEONE supplementation. Additionally, supplementation with 300 or 600 mg LEONE/kg diet increased total protein, globulin, thyroid hormones, and immunoglobulins A, G, and M. At the same time, levels of cholesterol, triglycerides, liver enzyme activities, urea, creatinine, and cortisol were significantly reduced. At the micro-mechanism level, LEONE enhanced antioxidant defenses by increasing total antioxidant capacity, elevating key antioxidant enzyme activities (SOD, CAT, GSH-Px), and reducing oxidative stress markers such as malondialdehyde, protein carbonyls, and 8-hydroxy-2'-deoxyguanosine. Moreover, LEONE modulated inflammatory responses by significantly lowering tumor necrosis factor-α, interferon-γ, serum amyloid A, and Toll-like receptor levels, indicating a protective effect on cellular and molecular pathways under heat stress. Importantly, no significant differences were observed between the groups receiving 300 or 600 mg LEONE/kg for any of the blood chemistry assays. Histological assessments demonstrated that LEONE provided protection against heat stress-induced liver and kidney damage. In conclusion, LEONE supplementation improved growth, immunity, antioxidant capacity, and inflammatory status under heat stress, with an optimal dose of ~ 450 mg/kg diet specifically for maximizing growth performance and enhancing feed conversion efficiency.