Effects of Days on Concentrate Feed and Postmortem Aging on Carcass and Palatability Characteristics of Selected Muscles from Cull Beef Cows1

Twenty-four beef cows were selected to examine the effects of concentrate feeding on performance and to examine the effects of concentrate feeding and postmortem aging (10 or 20 d) on the triceps brachii lateral and long heads, infraspinatus, longissimus lumborum, psoas major, gluteus medius, tensor fascia latae, rectus femoris, and vastus lateralis. Cows were randomly assigned to a concentrate diet for 0, 42, or 84 d. Carcass characteristics were measured and Warner-Bratzler shear force, sensory evaluation, and collagen analyses were performed on selected muscles. Cow BW, ADG, and BCS increased (P < 0.02) after 84 d. Hot carcass weight, ribeye area, fat thickness, marbling, and muscling increased (P < 0.02) after 84 d. Soluble collagen content increased (P < 0.01) in the triceps brachii-long head and longissimus lumborum after 84 d. There was a days on concentrate × muscle interaction (P < 0.01) for Warner-Bratzler shear force with the longissimus lumborum and gluteus medius decreasing with increasing days. Sensory evaluation showed that steaks became more tender (P < 0.01) after 84 d and exhibited less (P < 0.01) off-flavor after 42 d. Extended postmortem aging (20 d) decreased (P < 0.01) Warner-Bratzler shear force and increased (P < 0.01) sensory tenderness; however, postmortem aging did not increase (P > 0.05) sensory off-flavor detection. Concentrate feeding of cull cows for 84 d improved carcass characteristics and the tenderness of several muscles. These muscles may be aged for 20 d postmortem to achieve maximal tenderness without detrimental off-flavor production.