Histology of longissimus muscle from 2-week-old and 8-week-old normal and callipyge lambs

There were no differences in proportion or sizes of myofiber types in longissimus from 2-wk-old lambs of the callipyge and normal genotypes. In 8-wk old lambs, the type I ovine myofibers were oxidative, the majority of type IIA myofibers were glycolytic, and the majority of type IIB myofibers were oxidative.