Sarcomere length in muscles of Romosinuano Creole cattle crossed with Brahman, in Córdoba, Colombia

Objective. To determine histologically the length of the sarcomeres (LS) in muscle samples from commercial cuts in Romosinuano by Brahman bovine bulls. Materials and methods. Eighteen (18) muscle cuts with four repetitions of ten bulls (approx. 24m of age and 525±28.9 kg) were analyzed for the measurement of the bands that make up the LS, by staining with hematoxylin - eosin. The number of “A bands” present at 20 μm in each of the slices were counted. Results. The general average of LS for the 18 cuts was 2.12 μm. The longest LS were observed in the iliopsoas (3.32 μm) and tensor fasciae latae (3.26 μm) muscles (both p>0.05), which were significantly longer (p<0.05) than those obtained for the biceps femoris (1.69 μm) and gluteus medius (1.71 μm) muscles, which were considered to have lower SL (both p>0.05). Conclusions. Differences in LS were found between several muscles that correspond to commercial cuts from Colombia. The differences are related to the type, location and arrangement of the muscle in the carcass during cooling. The iliopsoas muscle (sirloin or fillet), cataloged in the market as a fine cut due to its tenderness, was the one with the highest SL. This is preliminary work for a Colombian Creole cross; therefore, it is necessary to continue deepening studies that allow elucidating to what extent there is an effect of the breed and of the industrial processes (thermal treatment and disposal of the carcasses in cold chambers) on the LS; but also, about the cause/effect relationship between LS and meat tenderness.