Immunomodulatory action of vitamin E in systemic immunity and mammary gland of dairy cows fed silage

Abstract

Regions such as southern Brazil live with drastic weather changes between winter and summer, resulting in direct disorders in the pasture, avoiding gradual change between grasses, creating periods of forage empty, a fact that diminishes the supply of forage, as well as its nutritional value. In these moments it becomes common to supplementation with intensive foods preserved as silage, a process that can reduce up to 50% levels of vitamin E from food, nutrient integrate cellular antioxidant system, responsible for the reduction of oxidative stress and immune function such phagocytosis, chemotaxis and oxidative metabolism in ruminants.Thus, the present study sought to measure the immunomodulatory activity of vitamin E in dairy cows in the middle of the stage of lactation, supplemented with corn silage and maintained on transition pasture not fertilized. We conducted assessments of hemogram, blood neutrophil function and cellularity of mammary glands before and after application of two parenteral doses of alpha tocopherol. It was observed in the treated group a significant increase for the series variable red blood, and to blood leukocytes mainly by an increase in neutrophils. In milk, there was increased cellularity, mainly by mononuclear elevation. As there was an increase of neutrophils positive to NBT test, it is believed that alpha tocopherol reduced cellular oxidative stress, enhancing phagocytosis and respiratory burst of neutrophils and decreased lipoperoxidation of cell membranes increases the halfspan of blood cells and milk.