Comparison of the effects of Actogain or Optaflexx on finishing feedlot steer performance and carcass characteristics

ABSTRACTTwo approved ractopamine hydrochloride source options currently exist in the United States cattle feeding marketplace. A study was conducted to evaluate the effects of feeding Actogain (Zoetis Inc., Florham Park, NJ) relative to Optaflexx (Elanco Animal Health, Greenfield, IN) or a control diet (no β-adrenergic agonist) on growth performance and carcass characteristics. Steers (n = 2,083, initial BW = 512.2±37.7 kg) were slaughtered on 2 separate days; each day consisted of 5 blocks and 3 treatments per block. Each slaughter group was fed for a 35-d period in which Actogain and Optaflexx treatments were formulated to provide 30 mg/kg of ractopamine hydrochloride (DM basis). Data were analyzed as a randomized complete block design using individual contrast statements to compare between treatments when the overall treatment factor was significant (P < 0.05). Live performance data included BW, ADG, DMI, and G:F. Twenty-four hours after slaughter, carcass quality and yield attributes were evaluated for all carcasses. Cattle fed ractopamine hydrochloride (Actogain or Optaflexx treatments) had greater (P ≤ 0.02) BW (+1.5%), ADG (+15%), G:F (+17%), HCW (+2%), dressed carcass yield (+0.345 percentage points), and LM area (+2.4%) concurrent with reduced (P ≤ 0.02) DMI (−1.7%). Live performance (or carcass-adjusted live performance) did not differ (P ≥ 0.33) between ractopamine hydrochloride products. Yield grade, 12th rib fat thickness, and KPH percentage were not different (P ≥ 0.11) among treatments, whereas marbling score was reduced (P ≤ 0.01) in the Optaflexx (Small39) treatment versus control (Small52) or Actogain (Small49) treatments. Results of the study demonstrate that Actogain compared similarly to Optaflexx, and both Actogain and Optaflexx treatment groups had greater growth performance and dressed yield effects relative to the control group