Post-slaughter muscle energy metabolism and meat colour of South African production systems
were compared; steers (n=182) of Nguni, Simmental and Brahman crossbreds were reared on
pasture until A-, AB-, or B-age, and in feedlot until A- and AB-age. After exsanguination carcasses
were electrically stimulated (400 V for 15s); m. longissimus dorsi muscle energy samples were
taken at 1, 2, 4 and 20 h post-mortem and samples for meat quality studies were taken at 1, 7 and 14
days post-mortem. Production systems affected muscle glycogen, glucose, glucose-6-P, lactic acid,
ATP, creatine-P and glycolytic potential (P<0.05), with the muscles of feedlot carcasses having
faster glycolysis rate than pasture carcasses. Energy metabolites correlated (0.4<r<0.9) with meat
colour (CIE, L*a*b*), and (0.30.5) water holding capacity, drip loss, and Warner Bratzler shear
force. Muscle energy only affected muscle contraction of the A-age-pasture system (shortest
sarcomere length of 1.66 μm vs 1.75 μm and highest WBS of 6 kg vs 5 kg; 7 days post-mortem).The Agricultural Research Council (ARC) is acknowledged for their facilities and THRIP and the RMRDT for financial support.www. elsevier.com/locate/meatscihb201
