Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
Ruminant Clinic, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
J Dairy Sci. 2019 Dec;102(12):11428-11438. doi: 10.3168/jds.2019-16721. Epub 2019 Sep 20.
The objectives of this study were to evaluate postpartum serum calcium dynamics for different parity groups of dairy cows and to assess whether serum calcium concentration on d 0, 1, and 3 postpartum was associated with the risk of developing acute puerperal metritis (APM). The study took place on a commercial dairy farm in northern Germany and included 4,043 Holstein dairy cows. Calving difficulties, such as dystocia, twins, or stillbirth, were recorded. Blood samples were obtained on d 0, 1, and 3 after calving for analysis of serum calcium concentration. Animals were examined daily for clinical symptoms of retained placenta, APM, mastitis, and displaced abomasum until 10 d in milk. To determine serum calcium dynamics postpartum, we performed repeated-measures ANOVA with first-order autoregressive covariance. A logistic regression model was used to evaluate the association of serum calcium concentration with the risk of developing metritis. Serum calcium concentration was affected by time relative to calving, parity, and APM. Increasing parity negatively affected serum calcium concentration on d 0 and 1. Serum calcium concentration reached its lowest level on d 1 and 3 in multiparous and primiparous cows, respectively. The concentration increased from d 1 to 3 in multiparous cows and decreased from d 0 to 3 in primiparous cows. The association of APM and serum calcium dynamics varied by parity. On d 3, serum calcium concentration was significantly lower in animals with subsequent APM than in those without APM. The overall incidence of APM was 12.0% (primiparous cows, 20.4%; multiparous cows, 8.6%). An association existed between serum calcium concentration on d 3 after calving and APM. Primiparous cows had an odds ratio of 0.12 for serum calcium concentration on d 3, indicating that a primiparous cow with serum calcium concentration of 2.5 mmol/L had a 88% lower chance of developing APM compared with a cow with a concentration of 1.5 mmol/L. Multiparous cows had an odds ratio of 0.34 for serum calcium concentration on d 3, indicating that a multiparous cow with serum calcium concentration of 2.5 mmol/L had a 66% lower chance of developing APM compared with a cow with a concentration of 1.5 mmol/L. Primiparous cows with low serum calcium concentration had the highest predicted probability of developing APM. Our results reveal a dynamic in serum calcium concentration in the first 3 d in milk. Consequently, the day of sampling and the observed risk period for hypocalcemia are important when conducting epidemiological studies to evaluate associations between hypocalcemia and clinical diseases.
本研究的目的是评估不同胎次奶牛产后血清钙动态，并评估产后第 0、1 和 3 天的血清钙浓度是否与发生急性产后子宫炎（APM）的风险相关。该研究在德国北部的一个商业奶牛场进行，共纳入 4043 头荷斯坦奶牛。记录了产犊困难，如难产、双胞胎或死产。产后第 0、1 和 3 天采集血液样本，用于分析血清钙浓度。动物在产后 10 天内每天检查是否有胎盘滞留、APM、乳腺炎和皱胃移位的临床症状。为了确定产后血清钙动态，我们进行了重复测量方差分析，采用一阶自回归协方差。使用逻辑回归模型评估血清钙浓度与发生子宫炎风险的关系。血清钙浓度受产犊后时间、胎次和 APM 的影响。胎次增加对产后第 0 和 1 天的血清钙浓度有负面影响。初产和经产奶牛的血清钙浓度分别在产后第 1 天和第 3 天达到最低水平。在经产奶牛中，血清钙浓度从第 1 天增加到第 3 天，而在初产奶牛中，血清钙浓度从第 0 天减少到第 3 天。APM 与血清钙动态的关系因胎次而异。产后第 3 天，发生 APM 的动物血清钙浓度明显低于未发生 APM 的动物。APM 的总发生率为 12.0%（初产奶牛为 20.4%；经产奶牛为 8.6%）。产后第 3 天的血清钙浓度与 APM 之间存在关联。与血清钙浓度为 1.5 mmol/L 的奶牛相比，血清钙浓度为 2.5 mmol/L 的初产奶牛发生 APM 的几率低 88%（优势比为 0.12）。经产奶牛的血清钙浓度为 2.5 mmol/L 时发生 APM 的几率低 66%（优势比为 0.34）。初产奶牛的血清钙浓度较低，发生 APM 的预测概率最高。我们的结果揭示了产后第 1 至 3 天血清钙浓度的动态变化。因此，在进行评估低钙血症与临床疾病之间关联的流行病学研究时，采样日和观察到的低钙血症风险期非常重要。
