Combined Effects of Nano-Zinc Oxide and Sesame Oil on Growth Performance, Antioxidant Defense, and Mineral Metabolism in Growing Rabbits

Heat stress adversely affects productivity and oxidative balance in rabbits. This study evaluated nano-zinc oxide (Nano-ZnO), sesame essential oil (SEO), and their combination in growing rabbits under severe to very severe heat stress (maximum daily THI, 10-day averages, 29.47–30.58). Eighty V-line males (45 days; 1100 ± 55 g) were assigned to basal diet, Nano-ZnO (60 mg/kg), SEO (300 mg/kg), or both for 60 days. Growth, digestibility, carcass traits, serum biochemistry and minerals, antioxidant status, and liver Zn were measured. No mortality occurred. Body weight was higher in all supplemented groups at 85 and 105 days (p = 0.001); at 65 days, only Nano-ZnO and SEO groups differed from the control. Overall, 45–105-day gain was higher in all supplemented groups (p = 0.001) and feed conversion improved (p = 0.009), whereas interval gains differed by additive. Nano-ZnO increased feed intake; SEO reduced intake. SEO, alone or combined, enhanced dry matter and crude protein digestibility (p < 0.01), and ether extract digestibility was highest with the combination. Carcass yield was unchanged, but relative liver and kidney weights increased with the combination (p ≤ 0.018). Nano-ZnO elevated serum Zn and Mg and liver Zn, whereas Ca decreased; p was greatest with the combination (p < 0.001). Globulin increased and albumin/globulin ratio decreased in treated groups. SOD and GR activities and TAC increased, and MDA decreased in supplemented groups, with the largest responses for the combination, whereas GPx was not significantly affected. In conclusion, Nano-ZnO and SEO, alone or combined, were associated with improved growth performance, nutrient utilization, and redox balance under heat stress. Because treatments were compared by one-way ANOVA, no Nano-ZnO × SEO interaction was tested and the combination is described as a combined effect, not synergy; the higher relative organ weights and lower serum calcium require further evaluation.