Department of Animal Science, Universidade Federal de Viçosa, Viçosa, MG 36570-900, Brazil.
Nutricorp, Araras, SP 13601-000, Brazil.
J Anim Sci. 2021 Nov 1;99(11). doi: 10.1093/jas/skab322.
This study was designed to evaluate the timing of administration of the bovine appeasing substance (BAS) on performance and physiological responses of Bos indicus feedlot cattle. Nellore bulls (n = 100) were ranked by initial body weight (BW; 341 ± 18.5 kg) and assigned to receive BAS (n = 50) or placebo (CON; n = 50) on day -2 of the experiment. Treatments (5 mL) were applied topically to the nuchal skin area of each bull. Bulls were loaded into commercial livestock trailers immediately after treatment administration, transported for 880 km, and unloaded on day -1 at a commercial feedyard. On day 0, bulls within each treatment were again assigned to receive, in a 2 × 2 factorial arrangement, BAS or CON as described previously (25 bulls/treatment combination). Upon treatment administration on day 0, bulls were housed in 12 feedlot pens (3 pens/treatment) for a 108-d feeding period, which was divided into an adaptation (days 0-19), growing (days 20-60), and finishing (days 61-108) phases. Dry matter intake (DMI) was measured daily from days 0 to 108, whereas blood samples and hair from the tail switch were collected on days -2, 0, 19, 60, and 108. Administration of BAS prior to loading (day -2) improved ADG, FE, and DMI during adaptation and across the 108-d feeding period (P ≤ 0.08), resulting in greater (P = 0.03) hot carcass weight and dressing percentage upon slaughter on day 109. A treatment × day interaction was detected for serum glucose concentrations (P = 0.05), which was greater (P = 0.03) on day 60 of the feeding period in bulls receiving CON prior to loading. Administration of BAS at feedlot entry (day 0) improved DMI, ADG, and FE during adaptation (P ≤ 0.05), but it did not impact (P ≥ 0.18) performance and carcass traits during the 108-d feeding period. Bulls administered BAS prior to loading and at feedlot entry had less (P ≤ 0.05) mean serum cortisol concentrations across the 108-d feeding period (loading × feedlot entry interaction; P = 0.10) and greater (P ≤ 0.05) serum insulin concentration on day 60 (loading × feedlot entry × day interaction; P = 0.05). In summary, BAS administration prior to loading increased the overall feedlot performance of Nellore bulls. These outcomes were noted in bulls that received or not a second BAS administration at feedlot entry, suggesting that the benefits of BAS are exploited when this substance is administered before transport to the feedlot.
本研究旨在评估牛安抚物质（BAS）在印度瘤牛育肥牛性能和生理反应上的给药时间。内罗尔公牛（n = 100）根据初始体重（BW；341 ± 18.5kg）进行排名，并在实验的第-2 天被分配接受 BAS（n = 50）或安慰剂（CON；n = 50）。处理（5mL）被局部应用于每头公牛的颈背皮肤区域。在治疗后，公牛立即被装入商业牲畜运输车内，运输 880 公里，并在商业饲料场的第-1 天卸下。在第 0 天，每个处理内的公牛再次被分配，以接受之前描述的 2×2 因子安排，即 BAS 或 CON（每个处理组合 25 头公牛）。在第 0 天给药时，公牛被安置在 12 个饲养围栏（每个处理 3 个围栏）中进行 108 天的饲养期，分为适应期（第 0-19 天）、生长阶段（第 20-60 天）和育肥阶段（第 61-108 天）。从第 0 天到第 108 天，每天测量干物质采食量（DMI），而在第-2、0、19、60 和 108 天，从尾巴切换采集血液样本和毛发。在装载前（第-2 天）给予 BAS 可提高适应期和整个 108 天饲养期的 ADG、FE 和 DMI（P≤0.08），导致在第 109 天屠宰时更大（P=0.03）的热胴体重和屠宰率。在血清葡萄糖浓度（P=0.05）上检测到处理×天的交互作用，在装载前接受 CON 的公牛在饲养期的第 60 天更高（P=0.03）。在育肥场入口处给予 BAS 可改善适应期的 DMI、ADG 和 FE（P≤0.05），但在 108 天的饲养期内对性能和胴体性状没有影响（P≥0.18）。在装载前和育肥场入口处给予 BAS 的公牛在整个 108 天饲养期的平均血清皮质醇浓度较低（装载×育肥场入口的交互作用；P=0.10），在第 60 天的血清胰岛素浓度较高（装载×育肥场入口×天的交互作用；P=0.05）。总之，在装载前给予 BAS 可提高内罗尔公牛的整体育肥场性能。在接受或不接受 BAS 第二次育肥场给药的公牛中都观察到了这些结果，这表明在将牛运送到育肥场之前给予 BAS 可以利用其益处。
