title: Effect of South African beef production systems on post-mortem muscle energy status and meat quality.
abstract: Post-slaughter muscle energy metabolism meat colour of South African production systems were compared; steers (n=182) of Nguni, Simmental Brahman crossbreds were reared on pasture until A-, AB-, or B-age, in feedlot until A-AB-age. After exsanguination carcasses were electrically stimulated (400 V for 15 s). M. longissimus dorsi muscle energy samples were taken at 1, 2, 4 and 20 h. Post-mortem 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 glycolytic potential (P<0.05), with the muscles of feedlot carcasses having a faster glycolysis rate than pasture carcasses. Energy metabolites correlated (0.4<r<0.9) with meat colour (CIE, L*a*b*), (0.3<r>0.5) 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 highest WBS of 6 kg vs 5 kg 7 days post-mortem).
authors.affiliation: Animal Production Institute, Agricultural Research Council of South Africa, Private Bag X2, Irene 0062, South Africa. Lorinda@arc.agric.za
authors.forename: L
authors.initials: L
authors.lastname: Frylinck
authors.forename: P E
authors.initials: PE
authors.lastname: Strydom
authors.forename: E C
authors.initials: EC
authors.lastname: Webb
authors.forename: E
authors.initials: E
authors.lastname: du Toit
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena / Q000235:genetics; D000818:Animals; D001947:Breeding; D002417:Cattle; D003116:Color; D003401:Creatine / Q000378:metabolism; D004032:Diet; D004734:Energy Metabolism / Q000235:genetics / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008460:Meat / Q000032:analysis* / Q000592:standards; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism*; D011180:Postmortem Changes; D012518:Sarcomeres; D013019:South Africa; D013314:Stress, Mechanical; D014867:Water
chemical_list: D014867:Water; D019344:Lactic Acid; D019298:Glucose-6-Phosphate; D000255:Adenosine Triphosphate; D006003:Glycogen; D005947:Glucose; D003401:Creatine