Thornhill J B, Krebs G L, Petzel C E
Department of Environment and Primary Industries, 1301 Hazeldean Road, Ellinbank, Victoria, 3821, Australia.
Aust Vet J. 2015 Jan-Feb;93(1-2):26-30. doi: 10.1111/avj.12287.
To investigate the accuracy of both the optical and digital Brix refractometers compared with radial immunodiffusion (RID) for determining the immunoglobulin G (IgG) concentrations in dairy calf serum.
The experiment design was a cross-sectional survey of four dairy farms. Serum was sampled from 12 calves from each farm at approximately 48 hours of age.
Serum IgG concentrations of 48 calves were measured using RID and both types of Brix refractometer.
IgG concentrations measured by Brix refractometer scores correlated with RID results: 0.74 and 0.71 for the digital and optical devices, respectively. The minimum Brix score that identified calf serum with success of passive immunity (>1000 mg/dL RID IgG) with 100% accuracy was 10% for both devices. The optical and digital devices performed similarly at identifying IgG concentrations in calf serum, with a concordance of 87%.
Brix refractometer score ≥10% can be used to classify calves with successful transfer of passive immunity and the devices are sufficiently accurate for use as a simple, inexpensive on-farm tool for the monitoring of neonatal dairy calf immunity levels.
比较光学和数字式白利糖度折射仪与放射免疫扩散法（RID）测定犊牛血清中免疫球蛋白G（IgG）浓度的准确性。
实验设计为对四个奶牛场进行横断面调查。从每个农场大约48小时龄的12头犊牛中采集血清样本。
使用RID以及两种类型的白利糖度折射仪测量48头犊牛的血清IgG浓度。
通过白利糖度折射仪评分测得的IgG浓度与RID结果相关：数字式和光学式设备分别为0.74和0.71。两种设备识别被动免疫成功（RID IgG>1000mg/dL）的犊牛血清的最低白利糖度评分为10%，准确率均为100%。光学和数字设备在识别犊牛血清中IgG浓度方面表现相似，一致性为87%。
白利糖度折射仪评分≥10%可用于对被动免疫成功转移的犊牛进行分类，且这些设备足够准确，可作为一种简单、廉价的农场工具用于监测新生犊牛的免疫水平。
