Plasma amino acid status is useful for understanding intestinal mucosal damage in calves with cryptosporidiosis.

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.