IL9 and mastitis: The cytokine-cytokine receptor signaling pathway genes exclusively expressed in uninfected mother-daughter pairs (EPOR, IL9, IFNL3, CCL26, and IL26) and the DEGs involved in immune-related pathways identified in the current study (including CCL20, IL13, MMP3, and BLA-DQB), may contain sequence polymorphisms that could serve as genetic markers for susceptibility to mastitis caused by S. aureus infection.