In this Research Communication we report the measurement of total blood calcium concentration with a water hardness test kit (WHTK) in dairy cattle and compare the results to a reference method. The study was carried out on 107 Holstein Friesian cows from three commercial dairy farms in Sardinia (Italy). Blood samples were collected ≤7 d from calving and total serum calcium concentration was determined using a biochemical analyzer and a WHTK. The relationship between the laboratory results and the WHTK results was investigated using Spearman's rank correlation test and simple linear regression was determined. Sensitivity, specificity, negative and positive predictive values, intra and inter-assay coefficient of variation were also calculated. The test values were highly correlated with the laboratory values (R2 = 0.72, P < 0.001). Sensitivity and specificity were respectively 88 and 83% for the WHTK and intra and inter-assay coefficients of variation were 7.3 and 11.3% respectively. The WHTK was identified as a potential on-farm tool for monitoring early postpartum Ca concentrations at herd level.

中文翻译：

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在农场使用水硬度测试套件评估奶牛的总血钙水平

在本研究通讯中，我们报告了使用水硬度测试套件 (WHTK) 在奶牛中测量的总血钙浓度，并将结果与​​参考方法进行比较。这项研究是在撒丁岛（意大利）三个商业奶牛场的 107 头荷斯坦弗里西亚奶牛身上进行的。产犊后≤7 天采集血样，使用生化分析仪和 WHTK 测定总血清钙浓度。使用Spearman等级相关检验研究实验室结果与WHTK结果之间的关系，并确定简单的线性回归。还计算了敏感性、特异性、阴性和阳性预测值、测定内和测定间变异系数。测试值与实验室值高度相关（R2= 0.72,磷< 0.001)。WHTK 的敏感性和特异性分别为 88% 和 83%，批内和批间变异系数分别为 7.3% 和 11.3%。WHTK 被确定为在畜群水平监测产后早期钙浓度的潜在农场工具。