The folic acid supplementation also regulated many important genes associated with immune response such as MHC class II antigen (BLA-DQB), TNFRSF1A, CXCL8, CXCL10, PTAFR, CXCR1, CXCR5, and CCL5. Importantly, our previously published study [22] documented the up-regulation of the CXCR1, NFKBIA, SOCS3, Pim-1 proto-oncogene, serine/threonine kinase, dual specificity phosphatase 4, zinc finger CCCH-type containing 12A, and NFKBIA in mammary epithelial cells after infection by S. aureus in vitro, while these genes showed significantly downregulated status in folic acid treated cows. This evidence concerns the gene CXCR5 and infection.