We've known for years that certain nutrients, such as vitamin E and selenium, have a profound effect on the immune system — and, therefore, mastitis. For instance, when immune cells fight bacterial organisms, they produce toxic compounds known as free radicals. And when the immune cells die, they release these toxic compounds. Vitamin E plays an important role in neutralizing the toxic compounds, thus protecting the surrounding tissue from harm and prolonging the life of the remaining immune cells.
Numerous studies have found that supplemental vitamin E, in the presence of adequate selenium in the diet, significantly reduces the incidence of mastitis. Those are just a few examples. A good overview was provided at the joint NMC-Mid-Atlantic Consortium meeting in May by Bill Weiss, professor of nutrition at the Ohio Agricultural Research and Development Center. He discussed nutritional influences on the prevalence and severity of mastitis in dairy cows. He stressed the importance of proper body condition (i.e., not letting cows get too fat in late lactation and the dry period), along with feeding adequate amounts of trace minerals and vitamins. Selenium and vitamin E are especially critical, he said.