This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) at feedlot entry to receiving cattle. Angus-influenced steers (n = 342) from 16 sources were purchased from an auction yard on day –1, and transported (12 hr; 4 trucks) to the feedlot. Upon arrival on day 0, shrunk body weight (BW; 240 ± 1 kg) was recorded and steers were ranked by load, shrunk BW, and source and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 171) or placebo (diethylene glycol monoethyl ether; CON; n = 171). The BAS is a mixture of fatty acids that replicate the composition of the bovine appeasing pheromone. Treatments (5 mL) were topically applied to each individual steer on their nuchal skin area. Steers were allocated to 1 of 24 drylot pens (12 pens/treatment) and received a free-choice diet until day 46. Steers were assessed daily for bovine respiratory disease (BRD) signs, and feed intake was recorded from each pen daily. Steer unshrunk BW was recorded on days 7, 17, 31, 45, and 46. Shrunk BW on day 0 was added an 8% shrink to represent initial BW, and final BW was calculated by averaging BW from days 45 and 46. Blood samples were collected from 5 steers/pen on days 0, 7, 11, 31, and 45. Pen was considered the experimental unit. Steer BW gain was greater (P = 0.04) in BAS vs. CON (1.01 vs. 0.86 kg/d, SEM = 0.05). Feed intake did not differ (P = 0.95) between treatments, resulting in greater (P = 0.05) feed efficiency in BAS vs. CON (171 vs. 142 g/kg, SEM = 10). Plasma cortisol concentration was greater (P = 0.05) and plasma glucose concentration was less in CON vs. BAS on day 7 (treatment × day; P = 0.07 and <0.01, respectively). Mean plasma β-hydroxybutyrate concentration was greater (P < 0.01) in BAS vs. CON (3.23 and 2.75 mg/mL; SEM = 0.12). Incidence of BRD was greater (P ≤ 0.05) in BAS vs. CON from days 6 to 10 and days 19 to 23 (treatment × day; P < 0.01), although overall BRD incidence did not differ (P = 0.20) between treatments (82.4% vs. 76.6%, respectively; SEM = 3.2). A greater proportion (P = 0.04) of BAS steers diagnosed with BRD required one antimicrobial treatment to regain health compared with CON (59.3% vs. 47.6%, SEM = 4.2). Hence, BAS administration to steers upon feedlot arrival improved BW gain during a 45-d receiving period by enhancing feed efficiency. Moreover, results suggest that BAS improved steer performance by facilitating early detection of BRD signs, lessening the disease recurrence upon first antimicrobial treatment.

中文翻译：

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管理安抚物质以优化饲养场接收牛的性能和健康反应

该实验评估了在饲养场入口处使用牛安抚物质 ( BAS ) 对接收牛的影响。来自 16 个来源的受安格斯影响的阉牛 ( n = 342) 在第 –1 天从拍卖场购买，并运输（12 小时；4 辆卡车）到饲养场。在第 0 天到达后，记录收缩的体重 ( BW； 240 ± 1 kg)，并按负荷、收缩的 BW 和来源对阉牛进行排名，并分配接受 BAS（IRSEA Group，Quartier Salignan，法国；n = 171）或安慰剂（二甘醇单乙醚；CON；n= 171）。BAS 是一种脂肪酸混合物，可复制牛安抚信息素的组成。将治疗剂 (5 mL) 局部应用于每头牛的颈部皮肤区域。将阉牛分配到 24 个干场围栏中的 1 个（12 个围栏/处理），并在第 46 天之前接受自由选择的饮食。每天评估阉牛的牛呼吸系统疾病 ( BRD ) 症状，并每天记录每个围栏的采食量。在第 7、17、31、45 和 46 天记录转向未收缩 BW。在第 0 天收缩 BW 添加 8% 收缩以表示初始 BW，最终 BW 通过平均第 45 和 46 天的 BW 计算。在第 0、7、11、31 和 45 天从 5 头公牛/围栏收集。围栏被认为是实验单位。转向带宽增益更大 ( P= 0.04) 在 BAS 与 CON（1.01 与 0.86 kg/d，SEM = 0.05）中。处理之间的采食量没有差异 ( P = 0.95)，导致BAS 与 CON 的饲料效率更高 ( P = 0.05)（171 与 142 g/kg，SEM = 10）。在第 7 天（治疗 × 天；分别为P = 0.07 和 <0.01），CON 组的血浆皮质醇浓度更高（P = 0.05）并且血浆葡萄糖浓度低于 BAS 。BAS 与 CON（3.23 和 2.75 mg/mL；SEM = 0.12）中的平均血浆 β-羟基丁酸浓度更高（P < 0.01）。从第 6 天到第 10 天和第 19 天到第 23 天（治疗 × 天；P < 0.01），BAS 与 CON中 BRD 的发生率更高（P ≤ 0.05 ），尽管总体 BRD 发生率没有差异（处理之间的P = 0.20）（分别为 82.4% 与 76.6%；SEM = 3.2）。与 CON 相比，更大比例 ( P = 0.04) 的 BAS 公牛需要一种抗生素治疗才能恢复健康（59.3% 对 47.6%，SEM = 4.2）。因此，在饲养场到达时给阉牛施用 BAS 通过提高饲料效率提高了 45 天接收期内的体重增加。此外，结果表明，BAS 通过促进 BRD 迹象的早期检测来改善转向性能，减少首次抗菌治疗后的疾病复发。