Abstract: Muscle tissue is divided into 3 types:skeletal muscle, cardiac muscle and smooth muscle. Among them, skeletal muscle is the largest organ of livestock and poultry, accounting for about 40% of the body mass, and it consists of muscle fibers with different sizes, shapes and contents of muscle contractile proteins, which are essential for maintaining body posture, respiration and thermoregulation. A complex combination of extrinsic and intrinsic mechanisms regulates myogenesis at all stages of muscle fiber development, and relevant signaling mechanisms play a decisive role in this process. Skeletal muscle of livestock and poultry is the main source of meat products and the improvement of meat quality traits is an important goal of every livestock farm, a comprehensive understanding of myogenesis and related mechanisms is necessary. In this paper, the occurrence, types and regulatory mechanisms of muscle fibers were reviewed by integrating the literature related to muscle fiber research at domestic and international from 1987 to 2022, highlighting the genes and signaling pathways related to the developmental patterns of muscle fibers in livestock and poultry, and presenting the problems in current research on the regulatory mechanisms of muscle fibers in livestock and poultry to provide an outlook on the future research directions.

Key words: muscle fiber, muscle fiber development, molecular regulation, signaling pathway, gene