Impacts of Maternal Bovine Appeasing Substance Administered at Weaning on Behavioral and Physiological Adaptation of Beef Heifers to the Feedlot

The effects of administering 10 mL of maternal bovine appeasing substance (mBAS) or water (control; CT) at weaning (day 0) before transport on feedlot adaptation and efficiency were evaluated in twenty-two Angus-influenced heifers (<i>n</i> = 11/treatment) over 28 days. Body weight (BW), salivary cortisol, blood for complete blood cell count, rectal temperature, chute score and exit speed were collected on days 0, 14 and 27. Intake, feeding duration, frequency and rate, as well as activity and rumination were monitored daily using automated systems. Average daily gain (ADG) and gain-to-feed ratio (G:F) were calculated for each 14-day interval as well as for the entire feeding period. Treated heifers spent less time eating (<i>p</i> ≤ 0.06) on weeks 1 and 2, with greater feeding rate and activity (<i>p</i> < 0.01) in week 1, followed by reduced activity (<i>p</i> ≤ 0.05) in weeks 2, 3 and 4. Rumination was longer (<i>p</i> < 0.05) in weeks 3 and 4, coinciding with greater (<i>p</i> ≤ 0.05) final BW, ADG_0-27, ADG_14-27, and G:F_0-27, G:F_14-27. Lymphocyte and hematocrit were lower (<i>p</i> < 0.05) on days 14 and 27, respectively, and platelets tended to be greater (<i>p</i> = 0.08) than CT for the entire period. Treated heifers achieved numerically greater profit margins than CT. Overall, mBAS enhanced feedlot adaptability post-weaning, improving production efficiency, which may translate into potential profitability; however, this interpretation should be viewed cautiously considering some design limitations.