Selenium, vitamin E and vitamin A blood concentrations in dairy sheep flocks with increased or low clinical mastitis incidence

Objective of the study was to evaluate the relationship between blood concentrations of selenium, vitamin E and vitamin A with the incidence of acute clinical mastitis in dairy sheep. For this purpose, 13 flocks with increased (≥10%) and five flocks with small (<3%) incidence rate of clinical mastitis, were studied. In flocks with increased incidence rate, whole blood selenium and serum vitamin A blood concentrations were smaller (P < 0.001) compared with those in flocks with smaller incidence of the disease; no relationship between vitamin E blood concentration and mastitis incidence was found. Animals with mastitis associated with Staphylococcus aureus had smaller (P < 0.05) selenium, vitamin E and vitamin A blood/serum concentrations compared to healthy animals within the same flock; animals with mastitis associated with Mycoplasma agalactiae had smaller (P < 0.05) concentrations of selenium and vitamin A compared to healthy animals within the same flock (P < 0.05); finally, animals with mastitis associated with coagulase-negative staphylococci had smaller (P < 0.05) concentrations of selenium compared to healthy animals within the same flock. The results indicate a possible predisposing role of Se deficiency in ovine mastitis. Selenium status of ewes may possibly be used to indicate animals at risk to develop clinical mastitis. Reduced vitamin A serum concentration may also contribute to development of clinical mastitis.