Blood selenium, vitamin E, vitamin A, and beta-carotene concentrations and udder health, fertility treatments, and fertility.

We investigated the activity of glutathione peroxidase in whole blood; concentrations of vitamin E, vitamin A, and beta-carotene in serum; SCC; udder bacterial infections and the incidence of clinical mastitis; fertility treatments; and the success of first AI of 511 dairy cows for 1 yr. The mean Se content in whole blood and the concentrations of vitamin E, vitamin A, and beta-carotene concentrations in serum were 191 micrograms/L, 5.9 mg/L, 0.39 mg/L, and 12.9 mg/L, respectively. An increase in Se concentration in whole blood was associated with a decrease in all infections, including infections by Staphylococcus aureus, Actinomyces pyogenes, and Corynebacterium spp. (-17.7, -31.7, and -70.6%, respectively). There was no association among the different infections or SCC and concentrations of vitamin E, vitamin A, or beta-carotene, but an association existed between vitamin A concentration and SCC. The lower Se concentration in whole blood did not increase incidence of clinical mastitis. The Se concentration in whole blood (200 micrograms/L) was accepted as a target value to optimize udder health. The incidence of fertility disorders (anestrus, subestrus, cystic ovaries, or delayed ovulation) was 34.4%. The pregnancy rate following first insemination was 48.6%. No significant association was observed among Se in whole blood; concentrations of total vitamin E, vitamin A, or beta-carotene in serum; and fertility disorders or success of first AI.