Oxidative stress in bovine mastitis and the protective role of antioxidants: A review

Bovine mastitis is one of the most prevalent and economically significant diseases affecting dairy cattle, leading to reduced milk yield, compromised milk quality, and increased treatment costs. In recent years, oxidative stress has been recognized as a key pathogenic factor influencing the onset, severity, and persistence of both clinical and subclinical mastitis. During intramammary infection, excessive production of reactive oxygen and nitrogen species by activated neutrophils results in lipid peroxidation, protein oxidation, and DNA damage in mammary tissues, thereby exacerbating inflammation and tissue injury. This review critically summarizes the mechanisms of oxidative stress involved in bovine mastitis and highlights the alterations in major oxidative stress biomarkers such as malondialdehyde, thiobarbituric acid reactive substances, advanced oxidation protein products, and 8-hydroxy-2′-deoxyguanosine. Furthermore, the role of enzymatic antioxidants, including superoxide dismutase, catalase, and glutathione peroxidase, along with non-enzymatic antioxidants such as vitamins A, C, and E, glutathione, and essential trace minerals (selenium, zinc, and copper), is discussed in relation to mammary gland protection and immune modulation. Evidence suggests that depletion of antioxidant defences during mastitis increases susceptibility to oxidative damage and prolongs disease progression. Nutritional supplementation of antioxidants emerges as a promising and sustainable adjunct strategy for mastitis prevention and management, particularly in the context of increasing antimicrobial resistance. Overall, maintaining redox balance through adequate nutrition and antioxidant support is crucial for improving udder health, enhancing immune competence, and reducing the incidence and severity of bovine mastitis under dairy production systems.