LAUSR

This experiment compared health, performance, and economical responses of newly received high-risk cattle administered the maternal bovine appeasing substance (mBAS). Angus-influenced newly weaned steers (n = 120) were purchased from an auction facility. Steers arrived at the research feedyard on d -1 and an initial shrunk body weight (BW) was recorded (199 ± 1 kg). Steers were ranked by shrunk BW and assigned to 1 of 2 treatments at initial processing on d 0: a) 10 mL of a mBAS (Ferappease; FERA Diagnostics and Biologicals; College Station, TX) or b) 10 mL of mineral oil (CON; placebo). Treatments were applied topically to the nuchal skin area (5 mL) and above the muzzle (5 mL). Steers were vaccinated, dewormed, implanted, castrated, and received a metaphylaxis treatment at initial processing, and then distributed into 10 drylot pens according to BW and treatment (n = 12 steers/pen, 5 pens/treatment). Feed intake and incidence of bovine respiratory disease (BRD) were recorded daily (d 0 to 60). Blood and hair samples from the tail switch were collected on d 0, 14, 28, 42, and 60. Steers were sampled for nasal microbiota analysis via nasal swab on d 0, 14, and 28. Final shrunk BW was recorded on d 61. Values from d 0 were used as a covariate in each respective analysis. Steer BW gain and final BW did not differ between treatments (P ≥ 0.46). Incidence of BRD were also similar between mBAS and CON steers (56.7% for both treatments; P = 0.99). A greater (P = 0.04) proportion of mBAS calves diagnosed with BRD required a single antibiotic treatment to regain health (70.6 vs. 47.0%), while mortality was greater (P = 0.03) in CON calves diagnosed with BRD (17.6 vs. 2.9%). Relative abundance (%) of Mycoplasma in nasal microbiota was reduced (P < 0.01) in mBAS steers compared with CON (34.7 vs. 27.4%). Cortisol concentration of in hair from the tail-switch was less (P = 0.01) on d 28 for mBAS compared with CON steers. Administering mBAS improved (P ≤ 0.05) total pen-based (“deads-in calculation”) BW change (498 vs. 309 kg) and feed efficiency (0.148 vs. 0.097 kg/kg) during the 60-d receiving period, resulting in greater (P = 0.04) profit in mBAS vs. CON pens ($-123 vs. $1,000/pen). Collectively, administration of mBAS to steers at the beginning of a 60-d receiving period decreased physiological stress markers, improved immunocompetence, reduced mortality, and increased pen-based productivity and overall economical responses.