Evaluation of Ralgro® on pasture and subsequent feedlot performance and carcass merit of mexican crossbred steers

A pasture/feedlot field study was conducted to evaluate the effects of a single Ralgro® implant during the stocker phase on steer grazing performance and subsequent feedlot performance and carcass merit. A total of 2,764 steers of Mexican origin averaging 449 lb were assembled in Texas and shipped to Kansas, where they grazed on three intensively-early-stocked Flint Hills pastures. At initial processing, the steers were individually weighed and randomly assigned to either a non-implanted control group or a Ralgro implant group. Ralgro steers gained more (23 lb; P\u3c0.01) than controls during the 82- to 93-day grazing phase. Following the grazing phase, all steers were shipped to a commercial feedlot in southwestern Kansas where steers from each pasture were individually weighed and given a single Component E-S® implant. Immediately after processing, steers from each pasture were sorted into either a light- or heavy-weight pen, regardless of pasture implant treatment, resulting in six feedlot pens. Days on feed ranged from 127 to 197. Control steers gained faster (P\u3c0.01) during the feedlot phase; however, Ralgro steers had higher cumulative weight gains across the combined pasture and feedlot phases (P\u3c0.01) and averaged three fewer days on feed (P\u3c0.05). There were no significant differences for marbling, fat thickness, ribeye area, KPH fat, or yield grade. Ralgro steers had lower (P\u3c0.05) quality grades because of a higher incidence (P\u3c0.001) of steers with B and C carcass maturities