Developmental characteristics of skeletal muscle in goose during the embryonic and early post-hatching periods.

Geese exhibit relatively low meat production and growth efficiency compared to broilers and ducks, with muscle fiber being key determinant of meat yield. The embryonic stage and early post-hatching period are critical for muscle fiber differentiation and hypertrophy. However, the muscle development of geese in these stages remains unclear. In this study, Yangzhou geese during embryonic stages (E15, E19, E21, E23, E25, E27, and E29) and the early post-hatching periods (1 d, 3 d, 5 d, 7 d, and 28 d) were selected. The breast and leg muscles were dissected to characterize the morphological traits and types of muscle fibers. Our results indicated that muscle fiber development in the breast and leg muscles follows an asynchronous pattern. Leg muscle differentiation began at E21 and was largely completed between E23 and E25. During the first week after hatching, muscle fibers grew rapidly, reaching a diameter of 19.5 μm by 7 d. In contrast, breast muscle fiber development occurred later, with no fully developed muscle fiber morphology observed throughout the entire embryonic period. Differentiation began at 1 d post-hatching. In addition, the breast muscle consisted entirely of fast-twitch fibers throughout all stages, whereas slow-twitch fibers first appeared in the leg muscles around E25. Between 5 and 28 d post-hatching, leg muscles shifted from slow- to fast-twitch fiber dominance. Taken together, our findings enhance understanding of skeletal muscle development in geese and will offer insights for improving meat yield via muscle fiber regulation.