Insulin-like Growth Factor 1 (IGF-1) is a highly conserved peptide growth factor that plays a central role in regulating growth, development, tissue maintenance, and metabolic processes in mammals including cattle (Bos taurus), dog (Canis lupus familiaris), dolphin (Delphinidae spp.), goat (Capra hircus), guinea pig (Cavia porcellus), horse (Equus caballus), cat (Felis catus), human (Homo sapiens), mink (Neogale vison), monkey (nonhuman primates), ferret (Mustela putorius furo), pig (Sus scrofa), and bat (order Chiroptera). The IGF-1 protein is identical at the amino acid level among these species, reflecting strong evolutionary conservation and essential biological functions. IGF-1 is produced primarily in the liver in response to growth hormone stimulation and circulates in the bloodstream bound to IGF-binding proteins (IGFBPs), which regulate its stability, transport, and tissue availability. It is also produced locally in many tissues, including muscle, bone, adipose tissue, and the nervous system, where it acts in autocrine and paracrine signaling. IGF-1 binds to the insulin-like growth factor 1 receptor (IGF1R), a transmembrane tyrosine kinase receptor, activating intracellular signaling pathways such as PI3K–AKT and MAPK that regulate cell proliferation, differentiation, survival, and metabolism. Functionally, IGF-1 promotes somatic growth by stimulating skeletal development, chondrocyte proliferation in growth plates, and bone formation, while also enhancing muscle protein synthesis and inhibiting apoptosis in multiple cell types. In addition to its growth-promoting effects, IGF-1 contributes to tissue repair, neuroprotection, immune regulation, and metabolic homeostasis, including modulation of glucose and lipid metabolism. Due to its broad biological roles and cross-species conservation, IGF-1 is widely studied as a key endocrine and paracrine regulator in developmental biology, veterinary science, aging research, and translational biomedical studies.