Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
J Dairy Sci. 2019 Jan;102(1):557-566. doi: 10.3168/jds.2018-15006. Epub 2018 Nov 22.
The objective of this study was to evaluate a filter system to harvest plasma to assess failure of passive transfer (FPT) in newborn calves. Blood samples (n = 227) for serum and plasma harvesting were collected via jugular vein puncture from Holstein calves aged 1 to 7 d from 4 commercial dairy herds in Northeast Germany. Serum IgG concentrations were determined using a sandwich ELISA. Failure of passive transfer was defined as IgG concentrations <10 mg/mL and used as a gold standard. One handheld optical refractometer (Euromex Holland, Arnhem, the Netherlands) and 2 digital Brix refractometers (device 1: HI 96801 digital refractometer, Hanna Instruments, Woonsocket, RI; device 2: Misco PA201, Misco, Solon, OH) were used to analyze total proteins in serum or plasma. The colostrum uptake of the calf can thus be monitored and calves with FPT can be identified. Serum was obtained through centrifugation. Plasma was obtained through either a filter system or centrifugation. For plasma filtration, approximately 2 mL of lithium heparin blood was injected into the inlet reservoir of a plasma filter (2-Drop-Filter, Pharmadoc, Lübeck, Germany) using a disposable syringe. Receiver operating characteristic curve analyses were used to determine optimum thresholds for each of the 3 devices using different media. Sixty-seven (30%) calves had FPT. For the handheld optical refractometer, the optimum threshold was 5.6 g/dL [sensitivity 70.1%; specificity 80.0%; positive predictive value (PPV) 60.1%; negative predictive value (NPV) 86.2%; area under the curve (AUC) 0.85] using serum. For centrifuged plasma, the optimum threshold was 6.3 g/dL (sensitivity 82.1%; specificity 68.1%; PPV 52.5%; NPV 89.9%; AUC 0.84), and for filtered plasma, the threshold was 6.0 g/dL (sensitivity 56.7%; specificity 90.0%; PPV 70.9%; NPV 82.9%; AUC 0.80). For device 1, the optimum threshold was 8.9% Brix (sensitivity 82.1%; specificity 63.8%; PPV 48.7%; NPV 89.5%; AUC 0.81), 9.4% Brix (sensitivity 76.1%; specificity 73.7%; PPV 55.4%; NPV 87.8%; AUC 0.80), using serum and centrifuged plasma, respectively. For device 2, the optimum threshold was 8.7% Brix (sensitivity 74.6%; specificity 76.2%; PPV 57.4%; NPV 87.5%; AUC 0.83), 9.5% Brix (sensitivity 80.6%; specificity 70.6%; PPV 54.0%; NPV 89.5%; AUC 0.83), and 9.2% Brix (sensitivity 58.2%; specificity 87.5%; PPV 66.6%; NPV 83.0%; AUC 0.80) using serum, centrifuged plasma, and filtered plasma, respectively. Based on the AUC, the 3 devices yielded comparable test characteristics to identify calves with FPT. In conclusion, a filter system can be used to facilitate the evaluation of FPT as a point of care technique in calves without the need for serum centrifugation.
本研究的目的是评估一种血浆采集过滤系统，以评估新生犊牛的被动传递失败（FPT）。从德国东北部的 4 个商业奶牛场采集了 1 至 7 日龄荷斯坦犊牛的颈静脉穿刺血样（n = 227），用于采集血清和血浆。使用夹心 ELISA 测定血清 IgG 浓度。将 IgG 浓度 <10mg/mL 定义为 FPT，并用作金标准。使用 1 个手持式光学折射计（荷兰 Euromex Holland，Arnhem）和 2 个数字 Brix 折射计（设备 1：Hanna Instruments，RI 的 HI 96801 数字折射计；设备 2：Misco，OH 的 Misco PA201）分析血清或血浆中的总蛋白。因此，可以监测犊牛的初乳吸收情况，并识别出具有 FPT 的犊牛。通过离心获得血清。通过过滤系统或离心获得血浆。对于血浆过滤，使用一次性注射器将大约 2mL 含肝素锂的血液注入血浆过滤器（2-Drop-Filter，Pharmadoc，吕贝克，德国）的入口储液器中。使用不同的介质，使用接收者操作特征曲线分析确定每个设备的最佳阈值。67 （30%）头犊牛有 FPT。对于手持式光学折射计，血清的最佳阈值为 5.6g/dL [灵敏度 70.1%；特异性 80.0%；阳性预测值（PPV）60.1%；阴性预测值（NPV）86.2%；曲线下面积（AUC）0.85]。对于离心血浆，最佳阈值为 6.3g/dL（灵敏度 82.1%；特异性 68.1%；PPV 52.5%；NPV 89.9%；AUC 0.84），对于过滤血浆，阈值为 6.0g/dL（灵敏度 56.7%；特异性 90.0%；PPV 70.9%；NPV 82.9%；AUC 0.80）。对于设备 1，最佳阈值为 8.9%Brix（灵敏度 82.1%；特异性 63.8%；PPV 48.7%；NPV 89.5%；AUC 0.81），9.4%Brix（灵敏度 76.1%；特异性 73.7%；PPV 55.4%；NPV 87.8%；AUC 0.80），分别使用血清和离心血浆。对于设备 2，最佳阈值为 8.7%Brix（灵敏度 74.6%；特异性 76.2%；PPV 57.4%；NPV 87.5%；AUC 0.83），9.5%Brix（灵敏度 80.6%；特异性 70.6%；PPV 54.0%；NPV 89.5%；AUC 0.83），和 9.2%Brix（灵敏度 58.2%；特异性 87.5%；PPV 66.6%；NPV 83.0%；AUC 0.80），分别使用血清、离心血浆和过滤血浆。基于 AUC，这 3 种设备在识别具有 FPT 的犊牛方面具有可比的测试特征。总之，过滤系统可用于在不需要血清离心的情况下作为一种床边技术来评估 FPT。
