Antioxidant chemistry and its role in mitigating oxidative stress in animals.

Oxidative stress is a major physiological challenge in poultry and livestock production, arising from an imbalance between reactive oxygen and nitrogen species generation and the antioxidant defense systems of animals. Stressors such as heat, high stocking density, transport, nutritional imbalances, and disease pressure exacerbate oxidative damage under intensive production conditions, leading to impaired immunity, reduced productivity, compromised meat quality, and increased disease susceptibility. Excessive reactive species negatively affect the immune, muscular, reproductive, digestive, and nervous systems. Although animals possess enzymatic and non-enzymatic antioxidant defenses, these mechanisms are often insufficient under high oxidative load, necessitating dietary antioxidant supplementation. Oxidative stress also interacts closely with immune function, inflammatory responses, and thermal stress, particularly heat stress, which intensifies the production of metabolic reactive oxygen species. Dietary antioxidants, including vitamins E and C, selenium, zinc, and plant-derived compounds, have demonstrated protective effects by mitigating oxidative damage, enhancing immune responses, and improving performance and product quality. Advances in oxidative stress biomarkers and analytical techniques have improved assessment accuracy, while emerging strategies, including precision nutrition, nanotechnology-based delivery systems, and regenerative therapies, offer promising avenues for management. Addressing oxidative stress through integrated nutritional, environmental, and therapeutic approaches is essential for sustainable poultry and livestock production.