BACKGROUND: Immune system is regulated by circadian rhythms, which promote inflammation and facilitate pathogen elimination. Antimicrobial peptides secreted by milk somatic cells and mammary gland epithelial cells play a crucial role in protecting the mammary gland from pathogenic invasion and mastitis. In this study, we aimed to investigate the circadian rhythms of clock gene and antimicrobial peptide gene expression in goat milk somatic cells, as well as the circadian variation in antimicrobia...