Histological Characteristics of Skeletal Muscles Across Avian Species: Links with Muscle Growth and Meat Quality

Poultry meat production has increased substantially worldwide through selection for rapid growth, feed efficiency, and high meat yield. These objectives, however, have been associated with increasing variation in muscle characteristics and meat quality, particularly in fast-growing birds. This review synthesizes the available literature on the histological characteristics of skeletal muscles in nine avian species used for meat production, focusing on muscle fiber number, size, and fiber-type composition and their relationships with muscle growth and meat quality. Literature searches were conducted in Google Scholar, PubMed, Web of Science, and Scopus up to March 2026. The available evidence indicates that muscle fiber characteristics contribute to differences in muscle function, metabolic phenotype, and postmortem muscle transformation, but their effects on meat quality cannot be considered independently of the vascular, metabolic, and connective tissue environment of the muscle. This perspective is particularly relevant in rapidly growing birds, especially broilers, in which pronounced fiber hypertrophy may exceed the capacity of surrounding tissues to maintain homeostasis and contribute to degeneration, inflammation, extracellular matrix remodeling, fibrosis, and growth-related breast muscle abnormalities. The review also highlights substantial differences in the availability, strength, and methodological consistency of histological evidence among avian species, with chicken being the most extensively studied and evidence for less-studied species remaining limited. Differences in staining procedures, fiber classification, muscle sampling, and measurement methods further restrict direct comparison among studies. Overall, muscle histology is important for understanding variation in growth and meat quality, but major knowledge gaps remain, particularly regarding direct links between muscle morphology and meat-quality characteristics.