This experiment evaluated health, physiological, and performance responses of high-risk cattle administered the maternal bovine appeasing substance (mBAS) during feedlot receiving. Angus-influenced, newly weaned male calves (n = 120) were purchased from an auction facility. Calves arrived at the research feedyard on day -1 and body weight (BW) was recorded upon arrival (199 ± 1 kg). Calves were ranked by arrival BW and received 1 of 2 treatments prior to initial processing (day 0): (1) 10 mL of an mBAS (Ferappease; FERA Diagnostics and Biologicals; College Station, TX) or (2) 10 mL of mineral oil (CON; placebo). Treatments were applied topically to the nuchal skin area (5 mL) and above the muzzle (5 mL). Calves were vaccinated against Clostridium and respiratory pathogens, dewormed, implanted, band-castrated, and received metaphylaxis at initial processing, and then distributed into 10 drylot pens according to arrival BW and treatment (n = 12 calves/pen, 5 pens/treatment). Calves were reapplied treatments (mBAS or CON) concurrently with booster vaccination on d 14. Feed intake and incidence of bovine respiratory disease (BRD) were recorded daily. Blood and hair samples from the tail-switch were collected on days 0, 14, 28, 42, and 60 for analysis of physiological variables. Calves were sampled for nasal microbiota analysis via swab on days 0, 14, and 28. Final shrunk BW was recorded on day 61 after 16 h of feed and water restriction. Calf BW gain and final BW did not differ between treatments (P ≥ 0.40). Incidence of BRD was similar (P = 0.99) between mBAS and CON (56.7% for both treatments; SEM = 6.45). 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%; SEM = 8.32), and mortality was greater (P = 0.03) in CON calves diagnosed with BRD (17.6 vs. 2.94%; SEM = 5.133). Relative abundance of Mycoplasma in nasal microbiota was reduced (P = 0.04) in mBAS calves compared with CON (34.7 vs. 27.4%; SEM = 2.35). Cortisol concentration in hair from the tail-switch was less (P = 0.01) on day 28 for mBAS calves compared with CON. Administering mBAS improved (P = 0.04) total pen-based liveweight change during the experiment (498 vs. 309 kg/pen; SEM = 65.2) and final pen-based total liveweight (2,676 vs. 2,484 kg/pen; SEM = 65.4). Administration of mBAS to high-risk cattle decreased physiological stress markers, reduced mortality, and increased pen-based productivity during a 60-d receiving period.
Keywords: feedlot receiving; health; maternal appeasing substance; performance; stress.
Beef cattle are exposed to several stressors during the initial days in the feedlot, which impair their immunity and lead to bovine respiratory disease (BRD). Strategies to mitigate stress upon feedlot arrival are warranted, including administration of the maternal bovine appeasing substance (mBAS). The mBAS is a mixture of fatty acids that replicate the composition of the original bovine appeasing pheromone. Administering mBAS has been shown to alleviate the physiological consequences elicited by stressful management procedures in beef cattle. In this study, male beef calves were purchased from a commercial auction facility soon after weaning, transported to the research feedyard, and assigned initial processing within a 48-h period. Calves were castrated and received a metaphylactic antibiotic treatment during initial processing, which are relevant management practices in US feedyards. In general, mBAS administration at initial processing and 14 d later decreased physiological stress markers, improved immunity parameters, and reduced mortality by 83% during a 60-d feedlot receiving period. Calf growth and BRD incidence were not affected, but the reduced mortality from mBAS administration increased total liveweight production by the end of the experiment. Therefore, this study provides additional evidence of the benefits from administering mBAS to beef cattle upon feedlot arrival.
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