Of the 12 co-expressed down-regulated genes, TFRC and MAPK6 are thought to be associated with immunity and mastitis, LARP1B and ODC1 are associated with reproductive traits, such as oestrogen and sperm quality (Park et al., 2016; Nasser et al., 2020; Zhao et al., 2020; Ghahramani et al., 2021; Zhong et al., 2021). Here, ODC1 is linked to mastitis.