8
Beta-Agonist Supplementation Does not Affect Movement, Signs of Lameness, or Animal Welfare Measures of Finished Steers at the Feedyard or Packing Plant
Market-ready steers (n = 793; BW = 633 kg) were evaluated for movement and lameness at both the feedyard and at the packing plant. Twelve pens of cattle (n = 66 steers/pen) were utilized in a randomized complete block design. Treatments were no beta-agonist (CON), zilpaterol HCl (8.33 mg/kg; ZH) fed for 20 d and withdrawn from feed for 3 d prior to slaughter, or ractopamine HCl (30.09 mg/kg; RH) fed for 28 d prior to slaughter. Steers were fed a high-concentrate diet for an average of 202 days before shipping 301 km to a commercial packing plant. The evaluator was certified to conduct animal welfare audits (Professional Animal Auditor Certification Organization) and blinded to treatment. Evaluation was conducted in November 2011 utilizing American Meat Institute guidelines. Beta-agonist supplementation did not affect any variables measured (P≥0.19). At the feedyard, cattle were evaluated at a known point of balking in the alley and as they exited a platform scale; at both locations, speed of movement (1 = walk, 2 = trot, 3 = run) was rated Acceptable (>75% walk or trot) for all treatments. Slips (0.30%) and Falls (0.0%) were minimal at the feedyard. Signs of lameness were observed in 1.50% for CON, 0.37% for ZH, and 0% for RH steers during weighing. While average speed of movement was not different when cattle were unloaded at the packing plant, RH cattle were rated Not Acceptable with only 60.5% walking or trotting (39.5% running). In addition, Slips and Falls were 13.38 and 0.39; 15.31 and 0.90; and 13.39 and 0.55% for CON, ZH, and RH steers, respectively, during unloading at the packing plant. Similarly, slightly more cattle were observed with signs of lameness at the packing plant (1.85%, 0.48%, and 1.15% for CON, ZH, and RH, respectively). Prod use was deemed acceptable (< 25%) for all treatments. Vocalization at stunning and inability to render an animal insensible with the first shot can be indicative of poor humane handling procedure and agitated animals. Vocalization (<3%) and first stun efficacy (>95%) were observed to be Acceptable for all treatments. Treatment did not affect movement, although more RH pens were scored as running at the packing plant. In addition, beta-agonist supplementation did not affect signs of lameness or other animal welfare measures at the time of shipment from the feedyard or after arrival at the packing plant.
Keywords: cattle, beta-agonist, animal welfare