MUSCLE FIBER TYPES OF SELECTED MUSCLES FROM BROILER CHICKENS IN RELATION TO AGE AND SEX1

Abstract

ABSTRACTChanges in muscle fiber types in relationship to chronological age and sex from selected back, breast and wing muscles of broiler chickens were characterized. Types of muscle fibers were distributed unevenly across the cross sections of back muscles with more red fibers in the deep part than in the superficial location. Very high proportions of αW fibers were found in breast and wing muscles. Muscle fiber area increased as chickens became older; however, the rate of area enlargement decreased with increasing chronological age. The sex of the chickens had no influence on either the proportion of muscle fiber types or areas. However, a sex × age interaction was observed for muscle fiber population in the Pectoralis superficialis muscle. Giant fibers were observed and these resembled βR and/or αR fibers. More giant fibers were observed in muscles consisting of higher proportion of αW fibers.