Relations between the oxidative status, mastitis, milk quality and disorders of reproductive functions in dairy cows - a review

Free radicals are natural final products of the intensive metabolism in cells located in organism high-yielding dairy cows. When the disturbing of homeostasis occurs, oxidative processes lead to oxidative stress which in high-yielding dairy cows cause inflammation of the mammary gland (mastitis). The inflammation can cause the reduction of milk yield and unfavourable changes in the milk composition, e.g. reduction in fat, casein proteins and calcium content with a simultaneous increase in the concentration of whey proteins, sodium and chlorine. Moreover, the activity of enzymes such a lipases, proteases, peroxides and the plasminogen in milk increases, negatively affecting its technological properties. In dairy cows the oxidative stress is associated with retaining placenta after calving and disrupting the activity of the corpus luteum, what affect the reproductive functions. The active immune response to inflammation leads to an increase in the secretion of other molecules having an adverse effect on embryo survival.