Immune, stress, and redox status biomarkers in newborn calves: Dynamics in serum and saliva during the first week of life

This study investigated serum and saliva immunity, stress, and redox status biomarkers in dairy calves during the first week of life. Blood and saliva samples were collected from 20 calves on days 0, 1, 2, and 7 for the analysis of biomarkers related to innate immunity (myeloperoxidase, calprotectin), cellular (adenosine deaminase), humoral immunity (gamma-glutamyl transferase), stress (α-amylase) and redox status (ferric reducing ability). Colostrum was given to all calves (3.8 ± 0.64 L) within 96 ± 73 min of birth. On day 7, some calves showed signs of neonatal calf diarrhea, most likely due to nutritional factors. All biomarkers were measurable in both fluids from day 0. Myeloperoxidase, Calprotectin and adenosine deaminase were higher in saliva than in serum and significantly increased after colostrum intake. Biomarkers of humoral immunity were higher in serum, increasing with colostrum intake. A positive correlation was found between gamma-glutamyl transferase and IgG and IgA in saliva. Biomarkers of stress and redox status did not appear to change with colostrum intake. Neonatal calf diarrhea led to increased concentrations of some of the biomarkers analyzed, such as myeloperoxidase and α-amylase. These results highlight the effect of colostrum on the cellular and humoral immunity of calves and provide insights into the potential use of saliva to monitor immune and stress status.