Effects of Concentrate Feeding on Cull Cow Carcass and Muscle Characteristics1

Twenty-four cull beef cows from the University of Florida beef ranches were selected in order to examine the effects of short-term feeding and postmortem aging on cull cow carcass characteristics and palatability attributes from selected muscles. Cull cows were randomly assigned to a treatment of 0, 42, or 84 d (n=8 each) on a limit fed concentrate ration of 25 lb/d prior to harvesting. Upon completion of the respective feeding period, cull cows were harvested at the University of Florida Meats Processing Center. Carcass data were collected at 24 h postmortem and nine muscles were excised from each carcass, steaks were cut and allowed to age for 10 and 20 d postmortem prior to Warner-Bratzler shear force (WBS) analysis and sensory panel (SP) evaluation. Cull cow hot carcass weight, ribeye area, 12th rib fat thickness, marbling and muscling increased (P<0.05) after cull cows were on feed for 84 d. As well, carcass lean was more youthful in appearance and brighter red in color after cull cows were fed a concentrate diet for 84 d. There was an interaction (P<0.05) for WBS with the Longissimus dorsi (loin) and Gluteus medius (sirloin) decreasing in WBS value the most as time on feed increased. Sensory panel evaluation showed that muscles increased (P<0.05) in tenderness at 84 d and had lower (P<0.05) off-flavor scores at 42 d. Prolonged postmortem aging (20 d) decreased (P<0.05) WBS values and increased (P<0.05) SP tenderness. However, extended postmortem aging of 20 d did not increase SP off-flavor detection.