Effect of dietary vitamin A on resistance to experimental Staphylococcus mastitis in mice.

Weanling mice (118) were fed a purified diet free of vitamin A for 3 wk and subsequently assigned to diets containing 10, 100 (4000 IU vitamin A/kg diet), or 300% of National Research Council recommended vitamin A. After 3 wk on the treatment diet all mice were bred and allowed to complete gestation. At 24 h postpartum, the left fourth abdominal mammary gland of each mouse was inoculated with Staphylococcus aureus (10(8) cells in .1 ml of saline/gland), and mammary gland infection was observed daily for 6 consecutive days. Liver vitamin A content was lowest in mice for 10% and highest for 300%. However, mice fed 10% showed normal growth and reproduction by small treatment differences in body weight changes, litter size at birth, and average pup weight. Mice fed 10 and 100% vitamin A showed more severe mammary gland inflammation after intramammary inoculation as opposed to mice fed 300%. Severity of mastitis in mice fed 100% vitamin A was similar to 10%. The number of mice classified as mastitic was also similar between 10 and 100% on days 1 and 2 postinoculation; however, on day 3 postinoculation mice fed 100% had a lower incidence of mastitis as opposed to 10%. Severity of mammary inflammation on days 4 through 6 were similar to those on day 3. Results showed a protective effect of dietary vitamin A supplementation against experimental Staphylococcus aureus mastitis in mice.

Vitamin A and beta-carotene in bovine and porcine plasma, liver, corpora lutea, and follicular fluid.

Bovine and porcine blood plasma, liver, corpora lutea, and follicular fluid were obtained from local abattoirs for study of distribution of vitamin A and beta-carotene. Retinol, retinyl esters, and beta-carotene were separated on alumina columns and subjected also to thin-layer chromatography. Retinol and retinyl esters were in corpora lutea and follicular fluid of both species. Concentrations of beta-carotene were high in bovine plasma, corpus luteum, and follicular fluid. In contrast, beta-carotene was lower in porcine tissues. Retinol, retinyl esters, and beta-carotene were closely correlated in bovine follicular fluid and blood plasma; however, correlations between bovine plasma and corpora lutea were not significant except for retinol. Only porcine retinol was closely correlated with plasma and follicular fluid, whereas correlations were nonsignificant between plasma and corpora lutea retinol, retinyl esters, and beta-carotene. Further studies, therefore, are needed to elucidate the physiological role of vitamin A and beta-carotene in regulating ovarian functions.