We hypothesize that some amino acid abnormalities in diarrheic calves are useful for understanding intestinal mucosal damage, as in humans. However, few reports have revealed the relationship between intestinal mucosal damage and plasma amino acids in diarrheic calves. Therefore, the aim of present study was to investigate whether there is a relationship between the amino acid status and plasma diamine oxidase (DAO) activity, which is known to be a biomarker for intestinal mucosal damage in diarrheic calves. Twenty Holstein calves aged 12.6 ± 4.2 days old were enrolled in this study. In the diarrhea group (n = 10), there were yellow loose feces within the rectum and Cryptosporidium parvum (C. parvum) was detected in all fecal samples. These calves were clinically normal except for diarrhea. All calves in the control group (n = 10) appeared to be healthy based on clinical findings with normal feces production and the absence of C. parvum. Plasma amino acid concentrations and DAO activity were measured. The relationships between plasma DAO activity and the concentration of each plasma amino acid were investigated using Spearman’s rank test. The plasma DAO activity was significantly lower in the diarrhea group (176.1 ± 60.1 IU mL⁻¹) than in the control group (309.3 ± 74.8 IU mL⁻¹) (p < 0.001). Furthermore, positive correlations were observed when comparing plasma DAO activity with histidine, proline, cystine, arginine, and glutamine concentrations. As a result of relationship between plasma DAO activity and amino acid status, it was concluded that plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

我们假设腹泻小牛中的某些氨基酸异常对理解肠道粘膜损伤很有用，就像在人类中一样。但是，很少有报道揭示肠粘膜损害与腹泻犊牛血浆氨基酸之间的关系。因此，本研究的目的是研究氨基酸状态与血浆二胺氧化酶（DAO）活性之间是否存在关系，已知该活性是腹泻小牛肠粘膜损伤的生物标记。20只年龄为12.6±4.2天的荷斯坦犊牛参加了这项研究。腹泻组（n  = 10）在直肠内有黄色的粪便散落，隐球菌（C. parvum）在所有粪便样本中均检测到）。这些小牛除腹泻外临床上均正常。 根据临床发现，正常粪便产生且无小隐孢子虫，对照组中的所有小牛（n = 10）似乎都健康。测量血浆氨基酸浓度和DAO活性。使用Spearman秩和检验研究血浆DAO活性与每种血浆氨基酸浓度之间的关系。腹泻组的血浆DAO活性（176.1±60.1 IU mL ^-1）显着低于对照组（309.3±74.8 IU mL ^-1）（p <0.001）。此外，将血浆DAO活性与组氨酸，脯氨酸，胱氨酸，精氨酸和谷氨酰胺浓度进行比较时，观察到正相关。由于血浆DAO活性和氨基酸状态之间的关系，可以得出结论，血浆氨基酸状态对于了解隐孢子虫病犊牛的肠粘膜损伤是有用的。