Distribution of βR, αR and αW Fibers in Turkey Muscles

This study was conducted to determine the fiber distribution in several turkey muscles and study the applicability of an improved fiber classification system to this species. The biceps femoris, sartorius, pectoralis, peroneus longus, semitendinosus and gastrocnemius muscles were obtained from adult turkeys and serial sections were histochemically stained for adenosine triphosphatase (acid- and alkali-stable ATPase), succinic dehydrogenase (SDH), glycogen and stained with hematoxylin and eosin. βR fibers (low ATPase) were extremely scarce in the pectoralis, biceps femoris and semitendinosus, although the biceps and semitendinosus displayed numerous (40–70%) red fibers (αR). Muscles which contained significant (βR-fiber populations include the peroneus longus (33%), gastrocnemius (10–75%) and sartorius (33–66%). The lateral biceps femoris is frequently used as a representative red muscle in turkey muscle quality research. The findings of this study indicate that the lateral biceps femoris may be representative of some, but not all, of the red muscles in the turkey. The findings also suggest that two frequently used systems of muscle fiber classification—the “red, intermediate, white” and the “red-slow and white-fast” classifications—do not correctly categorize turkey muscle fibers.