Plasma citrulline, arginine, nitric oxide, and blood ammonia levels in neonatal calves with acute diarrhea

Gultekin, Mehmet; Voyvoda, Huseyin; Ural, Kerem; Erdogan, Hasan; Balikci, Canberk; Gultekin, Gamze

Healthy control calves were routinely fasted for at least 8 hours before all numerical data within each study group were checked for normality by the Kolmogorov-Smirnov or Shapiro-Wilk tests. Nonnormally distributed variables were log transformed for analysis or analyzed by nonparametric methods. The measurements were analyzed in total and separately by group with the groups formed by diarrhea etiology, severity of diarrhea, degree of dehydration, and SIRS status. Diarrheic subgroups classified by the above mentioned criteria compared with age-matched healthy controls. For normally distributed data with or without transformation, Student's t test was used for comparisons between 2 groups (healthy controls vs all diarrheic calves), and 1-way ANOVA followed by Tukey's test was performed for comparisons among 3 or more groups (healthy controls and diarrheic subgroups). For data not normally distributed even after transformation, comparisons among groups were made by nonparametric tests (2 groups: Mann-Whitney U-test; 3 or more groups: Kruskal-Wallis test). Friedman's test was used to determine for changes in plasma CIT, ARG, NO, and blood ammonia concentrations over time in the healthy control group. Regression analysis was performed to assess the associations among plasma CIT, ARG, and NO, and blood ammonia concentrations and potential explanatory variables, namely age of calf (day), the presence of SIRS (no = 0; yes = 1) and etiology of diarrhea (noninfectious = 0; infectious = 1) in the diarrheic calves. Initially, simple linear regression was performed. A multiple linear regression by backward method was then constructed, which initially included any variables identified as P value <.2 on univariable analysis. One-way analysis of covariance (ANCOVA) was used to examine the influences of severity of diarrhea (mild = 0, moderate = 1, and severe = 2) and degree of dehydration (mild = 0, moderate = 1, and severe = 2) on plasma CIT and its related metabolites, after effect of the covariate, calf age, was controlled. Effect sizes were interpreted by Cohen's guidelines for the partial eta-squared (ηp2) values. 31 Data were expressed as mean (deviation) or median (ranges) based on the results of the normality test. All analyses were considered statistically significant at P < .05. Table 1 . In this study, mono-infection with C. parvum (42%) and coinfection with C. parvum + rotavirus (22%) were identified as the most common agents in diarrheic calves (Table 1) .