这项研究的目的是评估不同的分析方法,以确定奶牛的初乳质量,包括一种基于实验室的方法(ELISA)和4种农场测试。我们假设使用不同的分析方法,初乳免疫球蛋白G(IgG)浓度,即,ELISA(mg/mL),数字白利糖度折射计(%白利糖度),比色计(比重和mg/mL),流出漏斗(秒),侧流测定(mg/mL)与参考方法高度相关,放射免疫扩散(RID;mg/mL),并将产生可比的结果。初乳样品是从德国2个商业奶牛场的209头HolsteinFriesian奶牛中收集的。测量初乳重量和初乳温度。试验特性,如最佳阈值,灵敏度(Se),特异性(Sp),使用每个测试的受试者工作特征(ROC)曲线分析来确定曲线下面积(AUC)。在RID评估的209份初乳样本中,186(89%)样品质量高(≥50mgIgG/mL),而23个初乳样品(11%)显示质量差,IgG浓度低于50mg/mL。平均IgG浓度(±SD)为101.3±45.9mg/mL,范围为6.0至244.3mgIgG/mL。RID与ELISA的Pearson相关系数为r=0.78。与RID相比,农场测试的皮尔逊相关系数为:r=0.79(数字白利糖度折射计),r=0.58(比重计:比重),r=0.61(比色计:温度校正),r=0.26(流出漏斗)和r=0.43(侧流测定),分别。ELISA法鉴定优质初乳的最佳阈值为50.8mg/mL,灵敏度为91.3%,特异性92.3%,AUC为0.94。对于农场测试,灵敏度范围为95.7%(白利糖度折射计)至60.9%(侧流测定)。特异性范围从88.6%(侧流测定)到75.9%(温度校正后的比色计)。AUC范围为0.93(白利糖度折射计)至0.73(流出漏斗)。基于AUC,ELISA(0.94)和Brix折光法(0.93)可以被认为是高度准确的。总之,ELISA可以准确评估初乳质量。关于农场测试,只有数字白利糖度折射计和比色计足以确定初乳质量。
The objectives of this study were to evaluate different analytical methods to determine colostrum quality in dairy cattle, including one laboratory-based method (ELISA) and 4 on-farm tests. We hypothesized that the colostral IgG concentration using different analytical methods, such as ELISA (mg/mL), digital Brix refractometer (% Brix), colostrometer (specific gravity and mg/mL), an outflow funnel (seconds), and a lateral flow assay (mg/mL), were highly correlated with the reference method, radial
immunodiffusion (RID; mg/mL) and would generate comparable results. Colostrum samples were collected from 209 Holstein Friesian cows on 2 commercial dairy farms in Germany. Colostrum weight and colostrum temperature were measured. Test characteristics, such as optimum thresholds, sensitivity, specificity, and area under the curve (AUC) were determined using a receiver operating characteristic curve analyses for each test. Out of 209 colostrum samples assessed by RID, 186 (89%) samples had high quality (≥50 mg IgG/mL), while 23 colostrum samples (11%) showed poor quality with IgG concentrations less than 50 mg/mL. The mean IgG concentration (±SD) was 101.3 ± 45.9 mg/mL and the range was 6.0 to 244.3 mg/mL. The Pearson correlation coefficient (r) between RID and ELISA was r = 0.78. In comparison to RID, Pearson correlation coefficients for the on-farm tests were: r = 0.79 (digital Brix refractometry), r = 0.58 (colostrometer: specific gravity), r = 0.61 (colostrometer: temperature corrected), r = 0.26 (outflow funnel) and r = 0.43 (lateral flow assay), respectively. The optimal threshold to identify high-quality colostrum using ELISA was 50.8 mg/mL with sensitivity 91.3%, specificity 92.3%, and AUC of 0.94. For the on-farm tests sensitivity ranged from 95.7% (Brix refractometry) to 60.9% (lateral flow assay). Specificity ranged from 88.6% (lateral flow assay) to 75.9% (colostrometer: temperature corrected). The AUC ranged from 0.93 (Brix refractometry) to 0.73 (outflow funnel). Based on the AUC, ELISA (0.94) and Brix refractometry (0.93) can be considered highly accurate. In conclusion, the ELISA is accurate to assess colostrum quality. Regarding the on-farm tests only the digital Brix refractometer and the colostrometer were adequate to determine colostrum quality.