Peripartum Changes of Plasma and Milk Vitamin A and β-Carotene among Dairy Cows with or without Mastitis

Open Access
Publisher Website
Google Scholar
Abstract
Over 12 mo. the relationship between peripartum concentrations of vitamin A and .beta.-carotene in blood plasma and milk of 93 Holsteins with or without subsequent mastitis was studied. Blood was sampled daily from 7 days prepartum through 7 days postpartum and on alternate weeks through wk 10 of lactation. Milk samples were collected daily for 7 days postpartum and then biweekly for 10 wk. Somatic cell counts were on biweekly milk samples. Vitamin A and .beta.-carotene of blood plasma decreased rapidly prepartum to reach minimum concentrations at calving (vitamin A) or on day 4 to 6 postpartum (.beta.-carotene). Thereafter, both vitamin A and .beta.-carotene increased rapidly through 10 wk postpartum. Concentrations of vitamin A and .beta.-carotene in colostrum were higher than concentrations in milk. Cows with mastitis (somatic cells > 50,000 cells/ml milk) had lower vitanin A in blood plasma during days 0 to 7 and wk 2 and 4 postpartum than cows without mastitis. When data were analyzed with loge of somatic cell count as an independent regression variable, results were similar. In contrast to vitamin A, peripartum .beta.-carotene in blood plasma was higher among mastitic cows and was related to higher loge of somatic cell count. No significant difference was observed betweem mastitic and non-mastitic cows for vitamin A and .beta.-carotene in milk. Lower concentrations of plasma vitamin A and higher concentrations of .beta.-carotene during the immediate postpartum period were associated with higher milk somatic cell counts among dairy cows during lactation.