Impact of oxidative stress on the health and immune function of dairy cattle.

Oxidation and the production of free radicals are an integral part of aerobic metabolism. A variety of reactive oxygen species (ROS) are produced by normal metabolic processes and by certain leukocyte populations during defense against disease. Accumulated scientific evidence supports the concept that oxidative damage of tissues and cellular components are either a primary or secondary cause of many human diseases. Unfortunately, considerably less is known about how oxidative stress can affect veterinary health and well-being, particularly during times of high metabolic activity. The performance of high producing dairy cattle can be optimized to a certain extent by supplementing diets with optimal levels of micronutrients with antioxidant capabilities. However, oxidative stress continues to be a problem in transition cows. Innovative approaches are needed to enhance the antioxidant defense mechanisms of dairy cattle during times of increased metabolic demands.