Effects of in vitro supplementation with alpha-tocopherol and selenium on bovine neutrophil functions: implications for resistance to mastitis.

A low vitamin E/selenium status has been associated with increased vulnerability of dairy cattle to mastitis. Since polymorphonuclear leucocytes (PMN) provide the major cellular defence mechanism within the mammary gland, the effect of in vitro supplementation with vitamin E and selenium on the function of these cells was investigated. Both vitamin E and selenium enhanced the chemotactic and random migration of PMN and increased the production of superoxide following stimulation with phorbol myristate acetate. Vitamin E, but not sodium selenite, was also found to enhance the phagocytosis of opsonised Staphylococcus aureus by PMN. No synergistic effects of the two nutrients were observed. These results obtained in vitro may indicate the potential benefits of in vivo supplementation of dairy cows with vitamin E and selenium in terms of enhancing their natural resistance to mastitis.