Effects of administering the maternal bovine appeasing substance on growth performance, cortisol level and carcass characteristics of finishing feedlot cattle

This experiment evaluated physiological and performance responses of feedlot steers administered the maternal bovine appeasing substance (<b>mBAS</b>) during the finishing period (day 0 to 178). Steers used in this experiment were the same used to evaluate mBAS during the receiving period whose results have been published (Pickett et al., 2024). After the receiving period, steers were fed a growing diet for 65 days before the finishing period (without mBAS administration). On day 0, steers were assigned to topical administration (10 mL) of: 1) mineral oil on day 0 and 88 (<b>CON</b>), or 2) mBAS on day 0 and 88. Steers that were administered mBAS during the receiving period were also administered mBAS during the finishing period, and the same process applied to CON steers. Cortisol concentrations were measured in tail-switch hair on days 0 and 15. Steers received a growth-promoting reimplant on day 88. Total cattle used since the receiving period was 120 Angus steers, which were assigned in 10 drylot pens (12 steers/pen, 5 pens/treatment). Steers were slaughtered on day 179, and carcass variables were measured. Feed intake did not differ (<i>P</i> = 0.57) between treatments, but average daily gain was increased by 5.6 % (<i>P</i> < 0.04) in mBAS steers, improving their gain:feed by 7.6 % (<i>P</i> < 0.01). No treatment effects were noted (<i>P</i> ≥ 0.24) for carcass weight and variables. Collectively, mBAS administration to feedlot steers at the beginning of the finishing period and at reimplant improved growth rates without altering feed intake, suggesting the use of mBAS to promote productive efficiency of feedlot systems.