Oxidative stress-induced cytotoxicity and the role of dietary antioxidants in farm animals: A review

Abstract

Oxidative stress, resulting from an imbalance between reactive oxygen species (ROS) and antioxidant defenses, impairs animal health, immunity, reproduction, and productivity. This review summarizes the roles of key dietary antioxidants vitamin A, melatonin, essential trace minerals (copper, zinc, magnesium), flavonoids, polyphenols, and L-carnitine, in mitigating oxidative stress in farm animals. Vitamin A supports epithelial integrity, scavenges ROS, and upregulates antioxidant enzymes via redox-sensitive transcription factors. Melatonin functions as a potent free radical scavenger and activates the Nrf2 pathway to enhance antioxidant enzyme expression. Copper, zinc, and magnesium act as cofactors for enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), helping maintain redox homeostasis. Flavonoids and polyphenols, including quercetin, curcumin, and EGCG, exert antioxidant effects by scavenging ROS, chelating metal ions, and enhancing endogenous defense pathways. L-carnitine improves mitochondrial function, reduces ROS generation, and enhances glutathione activity, especially during stress conditions such as heat, transport, or weaning. Supplementation with these compounds across species has been shown to increase antioxidant enzyme activity, reduce oxidative biomarkers like malondialdehyde (MDA), and improve immunity, metabolic efficiency, and performance. These natural or synthetic antioxidants offer promising nutritional strategies to improve oxidative stability, health, and productivity in farm animals. Their integration into feed programs provides a sustainable and cost-effective approach to improving animal welfare and resilience under intensive production systems.