Effect of vitamin E on incidence of mastitis in dairy cattle

Incidence of mastitis was evaluated for 224 cows randomly assigned to one of two treatment groups: vitamin E supplemented and control. Vitamin E supplementation was started at drying-off and continued up to 90 d of next lactation at the rate of 1000 IU per cow per day and was then reduced to 500 IU daily for the remaining lactation period. Data on the concentration of vitamin E in blood plasma and milk, incidence of mastitis, and reproductive traits were analyzed by the least squares procedure. The model included the fixed effects of breed, parity, treatment, breed × parity, breed × treatment, parity × treatment, year, season, and days dry as a covariate. Concentrations of vitamin E in blood plasma and milk were higher (P < 0.05) in supplemented cows than in control cows. Supplementation of diets with vitamin E significantly lowered milk somatic cell count on day 112 of lactation but did not reduce the incidence of clinical mastitis. Vitamin E supplementation had no significant effect on the incidence of ...