Department of Ruminant Production, Institut de Recerca i Tecnologia Agroalimentàries, 08140 Caldes de Montbui, Spain.
Department of Ruminant Production, Institut de Recerca i Tecnologia Agroalimentàries, 08140 Caldes de Montbui, Spain; Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain.
J Dairy Sci. 2017 Sep;100(9):7427-7434. doi: 10.3168/jds.2016-12210. Epub 2017 Jul 6.
Dairy cows suffer blood Ca losses as lactation begins and might be affected by hypocalcemia in its clinical (total serum Ca concentration <1.50 mM) or subclinical form (total serum Ca concentration ≤2.14 mM). Several studies have suggested that hypocalcemia is associated with different health problems of the cow but results from different studies are not consistent. The objective of this study was to assess potential associations between subclinical hypocalcemia (SCHC) and displaced abomasum, intramammary infections, metritis, retained placenta, and ketosis. Also, the associations between SCHC and milk yield and reproductive function were evaluated. After discarding cows (32) with clinical hypocalcemia, a total of 764 cows from 6 different commercial farms were enrolled in this study. Blood samples were collected at 24 to 48 h postcalving and analyzed for total Ca concentration. Odds ratios of the different afflictions potentially associated with SCHC were calculated. Seventy-eight percent of the analyzed cows incurred SCHC. The occurrence of displaced abomasum, ketosis, retained placenta, and metritis was 3.7, 5.5, 3.4, and 4.3 times more likely, respectively, in cows that had SCHC than in cows with normocalcemia. Furthermore, the risk of incurring retained placenta or metritis increased in multiparous cows as serum Ca concentrations decreased compared with that in primiparous cows. Normocalcemic cows, independent of parity, were more likely to show their first estrus sooner after calving than SCHC cows, but no correlation was found between SCHC and other reproductive parameters. Different serum Ca concentration cutoffs were identified for several postpartum afflictions (≤1.93, ≤2.05, ≤2.05, and ≤2.10 mM for ketosis, retained placenta, metritis, and displaced abomasum, respectively). In conclusion, SCHC, defined as serum Ca ≤2.14 mM, is a frequent illness affecting the majority of the dairy cows with important repercussions on health. However, if SCHC were to be used to predict postpartum disease, different serum Ca cutoff points are likely to be needed because best predictive cutoff values varied among postpartum ketosis, displaced abomasum, retained placenta, and metritis.
奶牛在泌乳开始时会流失血液中的钙，并且可能会受到低血钙症的影响，其表现为临床（总血清钙浓度＜1.50mM）或亚临床（总血清钙浓度≤2.14mM）形式。一些研究表明，低血钙症与奶牛的不同健康问题有关，但不同研究的结果并不一致。本研究的目的是评估亚临床低血钙症（SCHC）与瘤胃变位、乳腺炎、子宫炎、胎衣不下和酮病之间的潜在关联。此外，还评估了 SCHC 与产奶量和生殖功能之间的关系。在排除了 32 头患有临床低血钙症的奶牛后，从 6 个不同的商业农场共招募了 764 头奶牛参与本研究。在产后 24 至 48 小时采集血样，分析总钙浓度。计算了与 SCHC 相关的不同疾病的优势比。分析的奶牛中有 78%发生了 SCHC。患有 SCHC 的奶牛发生瘤胃变位、酮病、胎衣不下和子宫炎的风险分别是血钙正常奶牛的 3.7、5.5、3.4 和 4.3 倍。此外，与初产奶牛相比，随着血清钙浓度的降低，经产奶牛发生胎衣不下或子宫炎的风险增加。与 SCHC 奶牛相比，无论初产与否，血钙正常的奶牛在产后更早地表现出第一次发情，但未发现 SCHC 与其他生殖参数之间存在相关性。对于几种产后疾病（酮病、胎衣不下、子宫炎和瘤胃变位的血清钙浓度临界值分别为≤1.93、≤2.05、≤2.05 和≤2.10mM），确定了不同的血清钙浓度临界值。综上所述，SCHC 定义为血清钙≤2.14mM，是一种常见的疾病，影响大多数奶牛，对健康有重要影响。然而，如果要使用 SCHC 来预测产后疾病，可能需要不同的血清钙临界值，因为最佳预测临界值因产后酮病、瘤胃变位、胎衣不下和子宫炎而异。
