Abstract：
This study aimed to evaluate the relationship between prepartum subclinical hypomagnesemia (pre-SHMg) and the occurrence of dystocia, metritis, clinical mastitis, lameness, and subclinical hypomagnesemia postpartum (post-SHMg) in pasture-based dairy cows. Also, the difference in means of prepartum magnesium (Mg) concentration by postpartum health events was evaluated. A total of 890 dairy cows from 32 commercial farms located in southern Chile were enrolled. Cows were examined twice, once between 30 and 3 days before and once between 3 and 30 days after calving. Blood samples were collected on both assessments, and cows were considered as having SHMg if serum total Mg < 0.65 mmol/L. On the postpartum visit, cows were evaluated for metritis and lameness. Information about clinical mastitis and dystocia was collected from on-farm records. Data were analyzed using multivariable mixed linear models and multivariable mixed logistic regression models. The overall prevalence of pre-SHMg was 9.9%, and its presence was associated with the occurrence of post-SHMg (odd ratio [OR] = 5.7; P < 0.0001) and metritis (OR = 3.1; P = 0.04). However, we did not detect an association between pre-SHMg and dystocia, clinical mastitis, or lameness after calving. Prepartum serum Mg concentrations were lower in cows that developed post-SHMg than those that did not (LSM ± SE = 0.75 ± 0.02 mmol/L vs. 0.83 ± 0.02 mmol/L; P < 0.0001). In conclusion, pre-SHMg was associated with a higher risk of post-SHMg and metritis in grazing dairy cows but not other postpartum health events.
摘要：
本研究旨在探讨产前亚临床低镁血症(pre-SHMg)与难产发生的关系,子宫炎,临床乳腺炎，跛行，牧场奶牛产后（SHMg后）和亚临床低镁血症。此外，通过产后健康事件评估了产前镁(Mg)浓度平均值的差异.来自智利南部32个商业农场的890头奶牛被录取。奶牛被检查了两次，一次在30和3天之前和一次在3和30天之后产卵。在两次评估中都收集了血液样本，如果血清总Mg<0.65mmol/L，则认为母牛患有SHMg。在产后就诊时，对奶牛的子宫炎和跛行进行了评估。从农场记录中收集有关临床乳腺炎和难产的信息。使用多变量混合线性模型和多变量混合逻辑回归模型分析数据。前SHMg的总体患病率为9.9％，它的存在与SHMg后（奇数比[OR]=5.7；P<0.0001）和子宫炎（OR=3.1；P=0.04）的发生有关。然而,我们没有检测到前SHMg和难产之间的关联，临床乳腺炎，产牛后或跛行。SHMg后发展的母牛的制剂血清Mg浓度低于未发展的母牛（LSM±SE=0.75±0.02mmol/L与0.83±0.02mmol/L；P<0.0001）。总之,在放牧奶牛中,SHMg前与SHMg后和子宫炎的风险较高相关,但与其他产后健康事件无关.
