Evaluation of the Maternal Bovine Appeasing Substance Administered at Arrival and Time of Reimplant on Feedlot Performance and Carcass Characteristics of Yearling Beef Steers

The objective of this experiment was to evaluate the effects of the maternal Bovine Appeasing Substance (mBAS), on feedlot performance, carcass characteristics, health outcomes, and hair cortisol concentrations for northern US origin yearling beef steers. Crossbred steers (n = 1754, initial BW = 423 kg, SD = 25 kg) were received on seven arrival dates over a 38-d period. Cattle were gate-sorted for randomization, assigned to pens (n = 20), and pens were randomly allocated to treatment prior to processing. Steers were blocked by source and arrival date (nine blocks) and received either (1) 10 mL of the mBAS (Ferappease®, FERA Diagnostics and Biologicals; College Station, TX) or (2) 10 mL of a mineral oil placebo (CON). Treatments were applied topically to the poll (5 mL) and above the muzzle (5 mL) at initial processing and again at reimplant (d 66 to 118). Feedlot personnel were blinded to treatment, and order of treatment processing was randomized for each starting block, and the chute was washed between each pen to avoid transfer of mBAS to control steers. Five steers per pen (n = 100) were randomly selected for hair sampling at processing and d 14 to evaluate cortisol concentrations. Steers were fed a high moisture corn-based finishing diet for 167 d and received Lubabegron (Experior®, Elanco; Greenfield, IN) for the final 36 to 63 DOF, standardized within arrival block. Continuous data were analyzed using a mixed model including treatment and block as fixed effects. Quality and Yield Grade data were analyzed as multinomial distributions. There was no difference in DMI or ADG between treatments (P ≥ 0.13), while carcass-adjusted G:F tended to improve for mBAS on a deads-in basis (P = 0.08). There was no difference in HCW, marbling score, or LM area between treatments (P ≥ 0.27), however, dressing percent tended to improve by 0.3 percentage points for mBAS (P = 0.10). Additionally, USDA Quality Grade and Yield Grade distributions did not differ between treatments (P ≥ 0.80). Administration of the mBAS did not impact the percent of cattle requiring 1 or 2 treatments, overall mortality rate, or hair cortisol levels from d 1 to d 14 (P ≥ 0.47). Topical application of mBAS at feedlot arrival and reimplant did not affect growth performance, health, or cortisol concentrations, but may modestly improve carcass-adjusted feed efficiency in yearling beef steers.