Abstract
The aim of this study was to examine clinically healthy cow’s udder milk microbiota and presence of cytokines in different seasons. Milk samples taken from the cows were checked for the presence of Gram-positive and Gram-negative bacteria, and the somatic cell count was detected. Immunohistochemistry methods were performed to detect interleukin (IL) -2, IL-4, IL-8, IL-10, IL-12, IL-17a, β-defensin-3, transforming growth factor (TGF)-ā1, interferon-ć and nuclear factor (NF)-źB presence in the milk. S. agalactiae, S. uberis, S. aureus, E. coli, and Klebsiella, Enterobacter, Citrobacter spp. were found in healthy cow’s milk. In the first round, the highest prevalence was observed for S. aureus. In the second round, the highest mean levels were observed for S. uberis, then followed S. aureus. IL-4, IL-17a and TGF-ā1 demonstrated the highest expression in the milk samples. NF-źB had the lowest expression among all factors. The presence of a rich bacterial microbiome (mostly S.aureus, S.uberis) in the milk of healthy animals, as well as changing bacterial species between in spring and autumn seasons occur as a result of both the immune state of the animal and many external factors, which consequently affects the amount of expressed cytokines.