Deelen S M, Ollivett T L, Haines D M, Leslie K E
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
J Dairy Sci. 2014;97(6):3838-44. doi: 10.3168/jds.2014-7939. Epub 2014 Apr 3.
The objective of this study was to evaluate the utility of a digital Brix refractometer for the assessment of success of passive transfer of maternal immunoglobulin compared with the measurement of serum total protein (STP) by refractometry. Blood samples (n = 400) were collected from calves at 3 to 6d of age. Serum IgG concentration was determined by radial immunodiffusion (RID), and STP and percentage Brix (%Brix) were determined using a digital refractometer. The mean IgG concentration was 24.1g/L [standard deviation (SD) ± 10.0] with a range from 2.1 to 59.1g/L. The mean STP concentration was 6.0 g/dL (SD ± 0.8) with a range from 4.4 to 8.8 g/dL. The mean %Brix concentration was 9.2% (SD ± 0.9) with a range of 7.3 to 12.4%. Brix percentage was highly correlated with IgG (r = 0.93). Test characteristics were calculated to assess failure of passive transfer (FPT; serum IgG <10 g/L). The sensitivity and specificity of STP at 5.5 g/dL were 76.3 and 94.4%, respectively. A receiver operating characteristic curve was created to plot the true positive rate against the false positive rate for consecutive %Brix values. The optimal combination of sensitivity (88.9%) and specificity (88.9%) was at 8.4% Brix. Serum total protein was also positively correlated with %Brix (r = 1.00) and IgG (r = 0.93). Dairy producers can successfully monitor their colostrum management and the overall success of passive transfer using a digital Brix refractometer to estimate IgG concentration of colostrum and calf serum.
本研究的目的是评估数字式糖度折射仪在评估母体免疫球蛋白被动转移成功与否方面的效用，并与通过折射法测量血清总蛋白（STP）进行比较。在犊牛3至6日龄时采集血样（n = 400）。通过放射免疫扩散法（RID）测定血清IgG浓度，使用数字式折射仪测定STP和糖度百分比（%Brix）。平均IgG浓度为24.1g/L [标准差（SD）±10.0]，范围为2.1至59.1g/L。平均STP浓度为6.0 g/dL（SD ± 0.8），范围为4.4至8.8 g/dL。平均%Brix浓度为9.2%（SD ± 0.9），范围为7.3至12.4%。糖度百分比与IgG高度相关（r = 0.93）。计算检测特征以评估被动转移失败（FPT；血清IgG <10 g/L）。STP在5.5 g/dL时的敏感性和特异性分别为76.3%和94.4%。绘制了一条受试者工作特征曲线，以针对连续的%Brix值绘制真阳性率与假阳性率的关系。敏感性（88.9%）和特异性（88.9%）的最佳组合在8.4%糖度时。血清总蛋白也与%Brix（r = 1.00）和IgG（r = 0.93）呈正相关。乳制品生产商可以使用数字式糖度折射仪成功监测他们的初乳管理以及被动转移的总体成功情况，以估计初乳和犊牛血清中的IgG浓度。
