The considerable increase in oxygen requirements during times of increased metabolic demands results in augmented
production of reactive oxygen species (ROS). An imbalance between increased production of ROS and the availability of antioxidant defenses needed to reduce ROS accumulation during the periparturient period may expose
cows to increased oxidative stress. Early studies suggested a role of oxidative stress in the etiologies of dairy cattle
disorders since supplementation with certain antioxidants could ameliorate the severity of a variety of metabolic and
infectious diseases