Department of Animal Production, Faculty of Veterinary Medicine, Box 393, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.
Clinic of Farm Animals, Department of Clinics, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.
Animal. 2021 Jan;15(1):100017. doi: 10.1016/j.animal.2020.100017. Epub 2020 Dec 10.
Hypocalcaemia is a common metabolic disorder of post-parturient dairy cows; enhancement of our knowledge regarding Ca dynamics would improve cow health and welfare. This study investigated the presence of time- and severity-related subclinical hypocalcaemia (SCHCa) patterns in Holstein cows after calving and their association with diseases during the first week of lactation. A total of 938 cows from nine herds were blood sampled on days 1, 2, 4 and 8 post-partum, and serum Ca concentration was measured with atomic absorption. Subclinical ketosis (serum β-hydroxybutyrate≥1.2 mmol/L) and cases of retained foetal membranes, metritis (MET), mastitis, ketosis and displaced abomasum (DA) were recorded. Using receiver operating characteristic (ROC) analysis, the SCHCa cut-off was identified at serum Ca ≤ 2.09 mmol/L. Hierarchical and two-step cluster analysis classified cows to seven clusters based on test day cow Ca records and overall SCHCa status. Two clusters (NORM and HIGH) included 318 normocalcaemic cows and five clusters (SCH-1 to -5) those that were at least once subclinically hypocalcaemic (n = 620). A second ROC analysis was performed in order to distinguish mild from severe cases of SCHCa in these 620 cows; this cut-off was identified at 1.93 mmol/L. The associated risk of disease with Ca clustership was assessed with generalized linear mixed models. Overall incidence of SCHCa was 66.1%. Clusters SCH-1 and SCH-2 included cows with short-term SCHCa of day 1 and day 2, respectively, while SCH-3 included cows with severe and prolonged SCHCa extending to day 4 and beyond. Clusters SCH-4 and SCH-5 included cows with delayed SCHCa, which culminated on days 4 and 8, respectively. Compared to NORM cows in HIGH had lower risk of MET and no cases of DA. Cows in SCH-3 had higher risk of being diagnosed with retained foetal membranes, DA or any disease during the study period. Cows in SCH-5 had higher risk of being diagnosed with ketosis, subclinical ketosis or any disease. In conclusion, there are multiple normocalcaemic and hypocalcaemic patterns that are differently associated with disease risk.
低钙血症是产后奶牛常见的代谢紊乱；提高我们对钙动态的认识将改善奶牛的健康和福利。本研究调查了荷斯坦奶牛产后不同时间和严重程度的亚临床低钙血症（SCHCa）模式及其与泌乳期第一周疾病的关系。从 9 个牛群中抽取了 938 头奶牛，在产后第 1、2、4 和 8 天采血，并使用原子吸收法测量血清钙浓度。记录亚临床酮病（血清 β-羟丁酸≥1.2mmol/L）和胎衣不下、子宫内膜炎（MET）、乳腺炎、酮病和皱胃移位（DA）病例。使用接收者操作特征（ROC）分析，确定血清 Ca≤2.09mmol/L 为 SCHCa 截断值。基于试验日牛 Ca 记录和整体 SCHCa 状态，采用分层和两步聚类分析将奶牛分为 7 个聚类。两个聚类（NORM 和 HIGH）包括 318 头正常血钙奶牛，五个聚类（SCH-1 至 -5）至少有一次亚临床低钙血症（n=620）。对这 620 头奶牛进行了第二次 ROC 分析，以区分 SCHCa 轻度和重度病例；该截断值确定为 1.93mmol/L。使用广义线性混合模型评估疾病与 Ca 聚类的相关性。SCHCa 的总发病率为 66.1%。聚类 SCH-1 和 SCH-2 分别包括第 1 天和第 2 天短期 SCHCa 的奶牛，而聚类 SCH-3 包括严重和持续时间延长至第 4 天及以后的 SCHCa 奶牛。聚类 SCH-4 和 SCH-5 包括延迟性 SCHCa 的奶牛，分别在第 4 天和第 8 天达到高峰。与 NORM 奶牛相比，HIGH 奶牛患 MET 和 DA 的风险较低。在研究期间，聚类 SCH-3 的奶牛患胎衣不下、DA 或任何疾病的风险更高。聚类 SCH-5 的奶牛患酮病、亚临床酮病或任何疾病的风险更高。总之，有多种正常钙和低钙模式与疾病风险不同相关。
