Eighty four Holstein cows were randomly allotted to four groups: group A was supplemented with 5mg Se/day, group B with 1000 IU vitamin E/day, group C with 5mg Se/day+1000 IU vitamin E/day and D was used as a control. The supplementation period started 30 days prior to probable parturition date and ended at parturition. Forage and concentrate samples were taken every 15 days for chemical, selenium and vitamin E analyses. Blood samples were taken before starting supplementation, at parturition, and at 30 and 60 days after parturition to determine the selenium serum levels. Tamis test was weekly done to detect clinical mastitis. Selenium supplemented cows had higher serum selenium concentration in comparison to the control group (P<0.05). The vitamin E (P<0.05) as well as selenium supplementation (P<0.08) decreased the incidence of clinical mastitis during the first 12 weeks of the lactation period.
antioxidant; milk quality; oral supplementation; prepartum; clinical mastitis
