Histochemical fiber types in 16 heavy-lamb skeletal muscles

- Contractile and metabolic fiber types in 16 heavy-lamb muscles were described.
- Relevant intermuscular differences in fiber typing were described.
- An objective metabolic-contractile muscle classification was proposed.

In order to histochemically describe contractile and metabolic fiber types in 16 heavy-lamb muscles, samples were taken from nine cross-bred heavy lambs. Relevant intermuscular differences were detected regarding fiber typing. Muscle Longissimus lumborum showed larger type II fibers than muscle Longissimus thoracis (P < 0.05). Muscles Triceps brachii caput longum and caput laterale differed in their contractile and metabolic characteristics (P < 0.05). Histochemical contractile and metabolic differences were also detected between muscles Cranial and Caudal Gluteobiceps, Supraspinatus and Infraspinatus, and Vastus lateralis and Rectus femoris (P < 0.05). Our present results contribute knowledge about sheep muscular histophysiology, and demonstrate for the first time the existence of specific intermuscular differences in fiber typing. The present study may also contribute to developing optimal commercial uses of each muscle for the meat industry.