Relationships between sarcomere length and basic composition ofinfraspinatus and longissimus dorsi muscle

The purpose of this study was to determine the relationship between sarcomere length and basic composition (water, protein, ash, collagen, and fat content including marbling) of beef muscles with fast-twitch glycolytic (longissimus dorsi muscle) and slow-twitch oxidative fibers (infraspinatus muscle) in Limousin bulls. Samples (n = 15) were obtained from federally inspected slaughter facilities, and animals used in the experiment were treated according to standard ethical norms. The shortest sarcomeres were observed for longissimus dorsi from striploin, and the longest for infraspinatus muscle. Additionally, the influence of both cut and animal was observed. In both cases of muscles, sarcomere length was positively correlated with marbling level and negatively correlated with protein content. Moreover, sarcomere length was very strongly correlated with marbling level in the case of longissimus dorsi et lumborum. Differences in sarcomere length were associated with cut and animal, and this correlation may partly explain differences in composition, especially in protein content.