This experiment was designed to evaluate the influence of prepartum vitamin A supplementation on incidence of mastitis in Holstein cows. Forty two cows were randomly distributed into blocks according to the parity and divided in two treatments: control and supplemented with 180,000IU vit.A/day. The supplementation started 30 days before probable parturition date up to parturition. The Tamis test was performed weekly for clinical mastitis detection, and milk samples were collected for somatic cell counts. Vitamin A treatment decreased the incidence of clinical mastitis (P<0.05), however no effect on milk somatic cell count was observed.

Oitenta e quatro vacas da raça holandesa foram distribuídas em quatro tratamentos (grupos): o grupo A recebeu 5mg Se/dia, o B recebeu 1000 UI vit. E/dia, o C 5mg Se + 1000 UI vit. E/dia e o D foi usado como controle. A suplementação foi iniciada 30 dias antes da provável data de parição, prolongando-se até o parto. Amostras do volumoso e do concentrado foram colhidas quinzenalmente para análise bromatológica completa e levantamento dos níveis de Se e de vit. E. O sangue foi colhido antes do início da suplementação, ao parto, aos 30 e aos 60 dias após o parto para determinação dos níveis de Se no soro sangüíneo das vacas. O teste de Tamis foi realizado semanalmente para detecção dos casos clínicos de mastite e iniciado logo após o parto, prolongando-se até a 12ª semana da lactação. Um mês após a suplementação, as vacas que receberam selênio apresentaram níveis séricos de Se superiores (P<0,05) aos do grupo-controle. A administração de vitamina E (P<0,05) e de selênio (P<0,08) diminuiu a incidência de mastite clínica nas 12 primeiras semanas de lactação.

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.