Peripartum decreases in serum concentrations of
vitamins A and E may contribute to impaired immune function in dairy cows. The objectives of this study were to describe peripartum serum concentrations of
alpha-tocopherol,
beta-carotene, and
retinol and their associations with disease risk. On 20 farms over 1 yr, blood samples were collected weekly from 1057 cows from 1 wk before expected calving until 1 wk postpartum. Serum concentrations of
alpha-tocopherol,
beta-carotene, and
retinol, as well as several biochemical variables were measured. Their associations with the risk of
retained placenta or clinical
mastitis were modeled separately with logistic regression, and the factors associated with the concentration of each
vitamin were modelled with mixed linear regression. Differences in
vitamin concentrations between 2 batches of sera analyzed 6 mo apart required stratification of statistical analyses. Accounting for the effects of parity, season, and twins, an increase in
alpha-tocopherol of 1 microg/mL in the last week prepartum reduced the risk of
retained placenta by 20%, whereas serum nonesterified
fatty acid concentration > or = 0.5 mEq/L tended to increase risk of
retained placenta by 80%. In the last week prepartum, a 100 ng/mL increase in serum
retinol was associated with a 60% decrease in the risk of early lactation clinical
mastitis. There were significant positive associations of peripartum serum concentrations among each of
alpha-tocopherol,
beta-carotene, and
retinol.