Prepartum circulating β–carotene and, more
importantly, vitamin E were lower for cows that
retained their placenta than for healthy cows (LeBlanc
et al., 2004). In fact, for every 1 μg/ml increase in
circulating vitamin E during the week preceding
parturition, the risk of retained placenta decreased by
21%. Furthermore, the decline in circulating
concentrations of β-carotene, vitamin A, and vitamin E
associated with parturition was more accentuated among
cows that developed mastitis during the first 30 days
postpartum than among healthy cows (LeBlanc et al.,
2004). In the last week prepartum, a 100 ng/ml increase
in circulating vitamin A concentration was associated
with a 60% decrease in the risk of clinical mastitis
(LeBlanc et al., 2004).