Correlation of blood metabolite concentrations and body condition scores with persistent postpartum uterine bacterial infection in dairy cows.

To analyze the relationship of blood metabolite concentrations and body condition score (BCS) with persistent bacterial uterine infection, specifically that caused by Trueperella pyogenes and anaerobic bacteria, uterine bacteriological swabs (n = 128) were collected from 64 Holstein cows at 5 (W5) and 7 (W7) weeks postpartum, and the percentage of neutrophils in the endometrium was evaluated. Blood glucose, total cholesterol (T-cho), blood urea nitrogen (BUN), non-esterified fatty acid (NEFA), and ß-hydroxybutyric acid concentrations were analyzed at 3 weeks (W-3) and 1 week (W-1) prepartum and W3, W5, and W7 postpartum. BCS were evaluated at W-3, W3, and W7. Blood glucose concentrations at W-3 and W-1 in cows with persistent bacterial infection were lower (P = 0.05) than in the rest of the cows. Total BUN concentrations in cows with persistent bacterial infection were lower (P < 0.01) than those in other cows, although the association between the pre or postpartum time and status of infection was not significant. Total NEFA concentrations in cows with persistent bacterial infection were similar to those in uninfected cows and cows positive for infection at W5 but not W7. Total BCS in cows with persistent bacterial infection were lower (P < 0.01) than those in cows positive for infection at both W5 but not W7 and W7 but not W5; however, the association between the pre or postpartum time and status of infection was not significant. Glucose concentrations at W-3 and W-1 negatively correlated with persistent bacterial infection at W5 and W7 (P < 0.01). BUN concentrations at W3 (P < 0.01), W5 (P < 0.05), and W7 (P < 0.05) and BCS at W3 (P < 0.01) negatively correlated with persistent postpartum bacterial infection. Decreased prepartum blood glucose concentrations might be an important risk factor for persistent postpartum bacterial uterine infection in dairy cows.

Plasma fluctuation in estradiol-17ß and bone resorption markers around parturition in dairy cows.

Blood samples were obtained sequentially from 10 dairy cows around the time of parturition to assess plasma fluctuations in estradiol-17ß (E2) levels in association with those of several bone resorption markers. Plasma E2 concentration increased sharply a few days prepartum and decreased quickly after parturition. In terms of bone resorption markers, the plasma level of tartrate-resistant acid phosphatase isoform 5b (TRAP5b) rose significantly, commencing 1 week prepartum, and was maintained at this level to a few days postpartum. The plasma concentration of carboxyterminal collagen cross-links of type-I collagen (CTx) increased significantly after parturition. These observations suggest that osteoclast-mediated bone resorption was activated after parturition when plasma E2 concentrations decreased.

Relationship between sex hormone fluctuations and biomarkers of bone resorption in bovine plasma during the oestrous cycle.

The objective of this study was to determine the potential influence of fluctuations in the sex hormones progesterone and oestradiol-17ß (E(2)), on biomarkers of bone resorption (hydroxyproline [HYP] and tartrate-resistant acid phosphatase isoform 5b [TRAP5b]) during the oestrous cycle of Holstein cows. Over the course of the study, plasma HYP concentrations did not change and alterations in the concentration of TRAP5b negatively correlated with E(2) levels: enhanced TRAP5b activity correlated with decreased E(2) concentrations below a defined level. This finding enhances the understanding of calcium homeostasis in post-partum dairy cows.