Bovine Macrophage Colony-Stimulating Factor (M-CSF) is a cytokine that regulates the development, proliferation, and survival of monocytes and macrophages in cattle (Bos taurus). M-CSF is produced by several cell types, including fibroblasts, endothelial cells, stromal cells, and epithelial cells, in response to tissue signals and inflammatory stimuli. Bovine M-CSF binds to the colony-stimulating factor-1 receptor (CSF1R), a receptor tyrosine kinase expressed on monocytes and macrophage lineage cells, activating intracellular signaling pathways such as PI3K–AKT, ERK/MAPK, and JAK–STAT that promote differentiation and maintenance of macrophage populations. Through these mechanisms, M-CSF supports macrophage-mediated immune surveillance, phagocytosis, tissue homeostasis, and inflammatory responses. Because macrophages play a central role in host defense and inflammatory regulation, M-CSF–mediated macrophage function is important for maintaining immune health and resistance to infection in cattle. In cell culture, recombinant bovine M-CSF is commonly used to promote differentiation of bovine monocytes into macrophages and to support macrophage proliferation and functional assays in vitro. Bovine M-CSF is also studied in animal model and veterinary research, including investigations of macrophage responses to important livestock pathogens such as Mycobacterium bovis, bovine viral diarrhea virus (BVDV), and Mycobacterium avium subsp. paratuberculosis, helping researchers better understand host–pathogen interactions and immune regulation in cattle.