Specific alterations in plasma histidine concentrations and diamine oxidase (DAO) activity were recently reported as a potential biomarker for intestinal mucosal damage in diarrheic calves. However, there are no data on the comparison of precision between histidine concentration and DAO activity in bovine plasma. The aim of the present study was to compare precision of histidine concentrations and DAO activities in plasma as a biomarker for the Cryptosporidium parvum (C. parvum)-associated intestinal mucosal damage in diarrheic calves. Thirty-two Holstein calves aged 12.2 ± 4.1 days old were enrolled in the present study; they were divided into C. parvum (n = 9), diarrhea (n = 11), and control (n = 12) groups based on the presence or absence of diarrhea and with or without C. parvum infection. Receiver operating characteristic (ROC) curves were used to characterize the sensitivity and specificity of each parameter for the C. parvum-associated intestinal mucosal damage. The proposed cut-off points for plasma histidine concentrations and plasma DAO activities for cryptosporidiosis in calves based on ROC analyses were < 55.8 nM and < 246.0 IU/ml, respectively. The sensitivities and specificities of the proposed diagnostic cut-offs were 88.9% and 82.6% for plasma histidine concentrations and 100.0% and 34.8% for plasma DAO activities, respectively. It was concluded that plasma histidine concentrations may be superior to plasma DAO activities as a specific biomarker for the C. parvum-associated intestinal mucosal damage in diarrheic calves.

最近报道血浆组氨酸浓度和二胺氧化酶（DAO）活性的特定改变是腹泻犊牛肠粘膜损伤的潜在生物标记。但是，尚无关于牛血浆中组氨酸浓度与DAO活性之间的精密度比较的数据。本研究的目的是比较血浆中组氨酸浓度和血浆DAO活性的精确度，作为腹泻小牛隐孢子虫（C. parvum）相关肠黏膜损伤的生物标志物。本研究招募了32只年龄为12.2±4.1天的荷斯坦犊牛。它们被分为微小隐孢子虫（Ñ  = 9），腹泻（Ñ  = 11），和控制（n  = 12）根据是否存在腹泻以及是否患有小肠衣原体感染进行分组。接收者操作特征（ROC）曲线用于表征小隐孢子虫每个参数的敏感性和特异性-相关的肠粘膜损伤。根据ROC分析，犊牛血浆组氨酸浓度和血浆DAO活性的建议临界值分别为<55.8 nM和<246.0 IU / ml。对于血浆组氨酸浓度和血浆DAO活性，建议的诊断临界值的敏感性和特异性分别为88.9％和82.6％。得出的结论是血浆浓度组氨酸可优于等离子体DAO活动为特异性生物标志物为小隐孢子虫在腹泻的小牛-相关肠粘膜损伤。