CXCL8 and mastitis: This result similar to previous studies such as Sharifi et al. (2018), who found CXCL8, CXCL2, and GRO1 were the top three genes associated with E. coli mastitis, and Han (2019) found CXCL2 and GRO1 were key genes in both the E. coli and the Staphylococcus aureus mastitis.