This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to beef calves at weaning on their performance, physiological responses, and behavior during a 42-d preconditioning program. Eighty calves (40 heifers and 40 steers; 90% British × 10% Nellore) were weaned at 233 ± 2 d of age (d 0), ranked by sex, weaning age and body weight (BW), and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal following dam separation. Within treatment, calves were allocated to 1 of 8 drylot pens (4 pens/treatment; pen being the experimental unit) and received a free-choice total mixed ration (TMR) from d 0 to 42, intake of which was assessed daily. Live behavior observations were conducted on d 1, 2, 4, 8, 16, and 32. Temperament was assessed and blood samples collected via jugular venipuncture on d -21, 0, 3, 7, 14, 28, and 42. Hair samples were collected from the tail switch on d 0, 14, 28, and 42. Calves were vaccinated against bovine respiratory disease viruses on d -21 and 0. Average daily gain from d 0 to 42 did not differ between treatments (P = 0.57), but was greater (P = 0.05) in BAS vs. CON calves from d 0 to 28. Intake of TMR was greater (P = 0.05) during the first week for BAS vs. CON calves (treatment × week; P = 0.08). Mean proportion of calves feeding simultaneously, and performance of social and play behaviors were greater (P ≤ 0.05) for BAS vs. CON calves. Escape attempts were greater (P & 0.01) for BAS vs. CON calves on d 1 (treatment × day; P = 0.03). Exit velocity was greater (P = 0.04) for CON vs. BAS calves on d 14 and tended (P = 0.10) to be greater for CON vs. BAS calves on d 7 (treatment × day; P = 0.03). Mean plasma concentrations of haptoglobin were greater (P = 0.02) in CON vs. BAS calves. Hair cortisol concentrations were greater (P = 0.05) in CON vs. BAS calves on d 14 (treatment × day; P = 0.03). Mean serum concentrations of antibodies against bovine viral diarrhea virus was greater (P = 0.02) in BAS vs CON calves. Collectively, BAS administration to beef calves at weaning alleviated stress-induced physiological reactions, improved temperament evaluated via chute exit velocity, enhanced humoral immunity acquired from vaccination, and appear to have accelerated adaptation to novel management scheme and environment.

中文翻译：

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在 42 天的预处理计划期间，在断奶时向小牛施用安抚物质以优化生产和健康反应。

该实验评估了在 42 天的预处理程序中对断奶时的牛犊施用牛安抚物质 ( BAS ) 对其性能、生理反应和行为的影响。80 头犊牛（40 头小母牛和 40 头公牛；90% 英国 × 10% Nellore）在 233 ± 2 日龄（第 0 天）断奶，按性别、断奶日龄和体重（BW）排序，并分配接受 BAS（ IRSEA Group，Quartier Salignan，法国；n = 40）或安慰剂（二甘醇单乙醚；CON; n = 40）。在大坝分离后，对每只动物的颈部皮肤区域局部施用处理剂(5mL)。在处理期间，小牛被分配到 8 个干场围栏中的 1 个（4 个围栏/处理；围栏是实验单位），并从第 0 天到第 42 天接受自由选择的总混合日粮 ( TMR )，每天评估其摄入量。在第 1、2、4、8、16 和 32 天进行实时行为观察。在第 -21、0、3、7、14、28 和 42 天评估气质并通过颈静脉穿刺收集血液样本。 头发样本在第 0、14、28 和 42 天从尾部开关收集。小牛在第 -21 天和第 0 天接种牛呼吸道疾病病毒疫苗。从第 0 天到第 42 天的平均日增重在处理之间没有差异（P = 0.57） , 但更大 ( P= 0.05) 在第 0 天到第 28天，BAS 与 CON 小牛。在第一周，BAS 与 CON 小牛的 TMR 摄入量更大 ( P = 0.05)（治疗 × 周；P = 0.08）。BAS 与 CON 小牛同时喂养的小牛平均比例，以及社交和游戏行为的表现更高（P ≤ 0.05）。在第 1 天（治疗 × 天；P = 0.03），BAS 与 CON 小牛的逃跑尝试更大（P & 0.01 ）。CON 与 BAS 小牛在第 14 天的退出速度更大（P = 0.04），并且在第 7 天（治疗 × 天；P = 0.03）CON 与 BAS 小牛的退出速度趋于更高（P = 0.10 ）。结合珠蛋白的平均血浆浓度更高（P= 0.02) 在 CON 与 BAS 小腿中。在第 14 天（治疗 × 天；P = 0.03），CON 与 BAS 小牛的毛发皮质醇浓度更高（P = 0.05 ）。在 BAS 与 CON 犊牛中，抗牛病毒性腹泻病毒抗体的平均血清浓度更高（P = 0.02）。总的来说，在断奶时对牛犊施用 BAS 减轻了应激引起的生理反应，改善了通过滑槽出口速度评估的气质，增强了疫苗接种后的体液免疫，并且似乎加速了对新管理方案和环境的适应。