Clinic for Ruminants, Clinical Department of Production Animals, University of Liege, Faculty of Veterinary Medicine, Liege, Belgium.
J Vet Intern Med. 2011 Nov-Dec;25(6):1465-9. doi: 10.1111/j.1939-1676.2011.00816.x. Epub 2011 Oct 7.
Failure of passive transfer (FPT) in beef calves can be detected by refractometry. Nevertheless, different models of refractometers are available, and few studies compare them for the detection of FPT.
To compare the accuracy of 4 different refractometers for measuring serum total protein concentrations in comparison with results obtained by the biuret method and, based on the serum IgG threshold of 1,600 mg/mL, to determine, for each refractometer, the optimal serum protein concentration's lowest threshold for successful passive transfer.
One hundred and eight healthy beef calves, 3-8 days of age.
Observational study. The concentrations of serum total proteins were determined with 4 different models of refractometers and compared with the biuret method by a Bland-Altman statistical method. The optimal serum protein concentration's lowest threshold for successful passive transfer was determined for each refractometer by receiver operating characteristic (ROC) analysis. In addition, the serum immunoglobulin G (IgG) concentration was compared with the serum gamma-glutamyl transferase (γ-GT) activity and with the total immunoglobulin concentration.
The refractometric measurements were highly correlated with those obtained by the biuret method. Serum total protein concentration threshold values of 56, 58, 54, and 56 g/L were found respectively for the Atago, Atago ATC, Wolf ATC, and digital ATC refractometers. Immunoglobulins were highly correlated with IgG, whereas γ-GT only reflected colostrum uptake by the calf.
All refractometers could be used for the assessment of passive transfer using their individual serum protein concentration threshold.
通过折射仪可以检测到肉牛犊的被动传递失败（FPT）。然而，可用的折射仪有不同的型号，很少有研究比较它们用于检测 FPT。
比较 4 种不同折射仪测量血清总蛋白浓度的准确性，并与比色法的结果进行比较，基于血清 IgG 阈值为 1600mg/ml，确定每种折射仪成功被动传递的最佳血清蛋白浓度最低阈值。
108 头健康肉牛犊，3-8 日龄。
观察性研究。使用 4 种不同型号的折射仪测定血清总蛋白浓度，并通过 Bland-Altman 统计方法与比色法进行比较。通过接收者操作特征（ROC）分析确定每种折射仪成功传递的最佳血清蛋白浓度最低阈值。此外，还比较了血清免疫球蛋白 G（IgG）浓度与血清γ-谷氨酰转移酶（γ-GT）活性以及总免疫球蛋白浓度。
折射仪测量结果与比色法高度相关。分别为 Atago、Atago ATC、Wolf ATC 和数字 ATC 折射仪，血清总蛋白浓度阈值分别为 56、58、54 和 56g/L。免疫球蛋白与 IgG 高度相关，而 γ-GT 仅反映了小牛对初乳的摄取。
所有折射仪都可以使用各自的血清蛋白浓度阈值来评估被动传递。
