Supplementary material for: Evaluation of test characteristics of two ELISA tests applied to bulk tank milk and claw trimming records for herd level diagnosis of bovine digital dermatitis using latent class analysis

Bovine digital dermatitis (DD) is an infectious claw disease with a negative impact on animal welfare and production. Treponema spp. is the main causative agent, and infected animals produce specific antibodies. Our aim was to estimate sensitivity (Se) and specificity (Sp) of two ELISA research tests, Medicago’s ELISA test and GD Animal Health’s in-house ELISA test, for detection of DD-associated Treponema antibodies in bulk tank milk (BTM). We used BTM samples form 154 Norwegian dairy cattle herds, 96 from an expected high and 58 from a low prevalence region. Both tests were evaluated separately against herd-level (aggregated) claw trimming records extracted from the Norwegian Dairy Herd Recording System using latent class models in a Bayesian analysis. Cut-off values were selected using an explorative approach, and both non-informative priors for all parameters and informative beta priors for distribution of Se and Sp of claw trimming were explored.

牛群数字性皮肤炎（DD）是一种影响动物福利和生产的传染性蹄部疾病。密螺旋体属（Treponema spp.）是其主要病原体，感染动物会产生特定的抗体。本研究旨在评估两种酶联免疫吸附测定（ELISA）研究测试，即Medicago公司的ELISA测试和GD动物健康公司的内部ELISA测试，在检测大量储奶（BTM）中与DD相关的密螺旋体抗体方面的灵敏性（Se）和特异性（Sp）。我们使用了来自154个挪威奶牛场的BTM样本，其中96个来自预期高发病率区域，58个来自低发病率区域。两种测试分别使用贝叶斯分析中的潜在类别模型，针对从挪威奶牛场记录系统中提取的群体级别（聚合）蹄部修剪记录进行评估。截止值通过探索性方法选取，并探讨了所有参数的非信息先验以及蹄部修剪灵敏性和特异性分布的贝塔先验。