Effect of breed on the muscle glycogen content and dark cutting incidence in stressed young bulls

Observations have shown relevant differences in the behaviour of Brown Swiss bulls and Pirenaico bulls. Because temperament is involved in the development of dark cutting beef (DC), the aim of this study was to investigate the influence of breed on muscle glycogen content and on the incidence of DC condition. Twenty-four Brown Swiss bulls and 24 Pirenaico bulls were used. The animals were divided into a stressed group (S) and a control group (C). In group S, bulls were mixed with unfamiliar animals overnight before slaughter. In group C, bulls were slaughtered immediately after arrival at the abattoir. The results show that the glycogen concentrations in m. longissimus dorsi and m. sternomandibularis from unstressed animals were similar in both the Brown Swiss and the Pirenaico breeds. The muscle glycogen concentration was depleted in all stressed bulls, nevertheless some low concentrations were insufficient to adversely affect the meat ultimate pH value. Finally, there was no influence of breed on the incidence of the dark cutting condition.