Comparison of conventional and organic beef production systems II. Carcass characteristics

Abstract

Carcass characteristics were evaluated as part of a comprehensive study comparing organic and conventional beef production systems. Preconditioned crossbred steers from conventional (C; n=24) and low-input (O; n=30) farming systems were randomly divided into two groups and assigned to either organic (o) or conventional (c) feedlot systems. Conventionally fed steers received an ionophore, implants on day 0 and 70, and an anthelmintic on day 0. Steers were fed individually using Calan Feed Access Doors. Each calf was fed to reach target end points of 567 kg body weight and 0.75 to 0.90 cm back fat measured between the 12th and 13th ribs using real-time ultrasound when steers approached the target weight. Fixed effect of production system was fitted with age of steers at the start of the feedlot phase as a covariate. Steers in the Cc system had the heaviest (P<0.05) hot carcass weights and Oo steers the lightest (P<0.01). Ribeye areas from Cc steers were larger than those from Oo (P<0.01) and Oc steers (P<0.05). Steers in group Cc had less back fat than Oc (P<0.01) and Oo steers (P<0.05). There was no effect of production system on kidney, pelvic and heart fat or dressing percentage. Fixed effect of finishing system only was also analyzed. Steers in conventional finishing had heavier (P<0.01) carcasses, larger (P<0.01) ribeyes and less (P<0.05) marbling than steers in organic finishing.