Variability of Muscle Fiber Size in Bovine Longissimus Dorsi

The variation in muscle fiber size of ten bovine l. dorsi muscles taken from the right and left sides of five animals was investigated using two different methods. The l. dorsi muscle was sampled at five positions along its length and at five cross-sectional locations within each position. A great deal of variation existed in muscle fiber size both among different positions along the l. dorsi muscle and among different locations within each position. The smallest fibers were found over the 12th rib and at the lateral edge of the muscle. The two methods for determining muscle fiber size gave similar, but not identical, results. The results indicate that studies pertaining to muscle fiber diameter or meat texture should carefully consider sampling procedures. Large and significant differences in l. dorsi muscle fiber size were found among animals of the same weight and grade.