Effects of implant strategy in extended stocker cattle programs and subsequent carcass characteristics

Objective: Our objective was to understand the effects of different implant protocols in a long-duration stocker program on high-quality forage and potential carryover effects into later production phases. Materials and Methods: In Oklahoma (OK) and Mississippi (MS), steers were grazed on cool-season annual pastures in fall 2018 through spring 2019. Steers were ran-domly assigned to 1 of 3 implant treatments: (1) Synovex One Grower (Zoetis) at d 0, (2) Component TE-G (Elanco Animal Health) at d 0, or (3) Component TE-G at d 0 and again at d 82 (OK) or d 85 (MS). Steers from each treatment were commingled in 2 (OK) or 3 (MS) pastures for 159 (OK) or 161 d (MS). At the end of the grazing sea-son, steers were finished in commercial feedyards, where they were implanted identically upon arrival. Steers were slaughtered when the pen was visually estimated at 1-cm backfat. Carcass data included hot carcass weight, rib-eye area, back fat thickness, and marbling score.Results and Discussion: Implant program had no sig-nificant effect on animal performance (weight and ADG) during the stocker phase (P > 0.39), but marbling score tended to be greater in the single Component TE-G versus the other 2 treatments (425 vs. 408 and 410, SEM = 5.9, P = 0.07).Implications and Applications: No evidence was found to recommend an extended-release implant or stock-er-phase reimplanting even in a relatively long grazing phase (up to approximately 160 d), and producers should consider selecting the least-cost implant protocol.