Differential Growth in the Supracoracoideus Muscles of Male and Female Turkeys

Abstract

SummaryThe growth of supracoracoideus muscles in male and female turkeys was measured at two week intervals for 20 weeks after hatching. Growth in weight of the supracoracoideus was closely related to growth of the adjacent pectoralis and coracobrachialis muscle. Growth curves for muscle length and fascicular length exhibited marked deceleration so that more than 75% of the length at 20 weeks had been reached by 10 weeks. Growth curves for weight, cross sectional area at the muscle midlength and myofibre diameter were approximately linear with 50% or less of the 20 week growth attainment being reached by 10 weeks. Supracoracoideus muscles in most males had a greater cross sectional area and were longer and heavier than those in females. At 20 weeks, the greater mass of supracoracoideus muscles in males was due to radial and not longitudinal myofibre growth.