The development of technologies that promote environmental stewardship while maintaining or improving the efficiency of food animal production is essential to the sustainability of producing a food supply to meet the demands of a growing population. As such, Elanco (Greenfield, IN) pursued an environmental indication for a selective β-modulator (lubabegron; LUB). LUB was recently approved by the United States Food and Drug Administration (FDA) to be fed to feedlot cattle during the last 14 to 91 d of the feeding period for reductions in gas emissions/kg of unshrunk final BW and HCW. A 4 × 2 factorial arrangement of treatments was used with the factors of dose (0.0, 1.38, 5.5, or 22.0 mg·kg−1 DM basis) and sex (steers or heifers). Three 91-d cycles were conducted (112 cattle/cycle) with each dose × sex combination being represented by a single cattle pen enclosure (CPE; 14 cattle/CPE) resulting in a total of 168 steers and 168 heifers (n = 6 replicates/dose). There were no interactions observed between dose and sex for any variable measured in the study (P ≥ 0.063). Five gases were evaluated for all pens based on CPE concentrations relative to ambient air: NH3, CH4, N2O, H2S, and CO2. Cumulative NH3 gas emissions were reduced by feeding cattle 5.5 and 22.0 mg·kg−1 LUB (P ≤ 0.023) and tended (P = 0.076) to be lower for the cattle fed 1.38 mg·kg−1 LUB compared with the negative controls (CON). The cumulative NH3 gas emission reductions of 960 to 1032 g, coupled with HCW increases (P ≤ 0.019) of 15 to 16 kg for all LUB doses vs. CON, led to reductions in NH3 gas emissions/kg HCW for all three LUB treatments (P ≤ 0.004). Similar to HCW, reductions in NH3 gas emissions/kg of unshrunk final BW were observed for all LUB doses (P ≤ 0.009) and were attributable to both decreases in NH3 gas emissions and numerical increases in BW. Dose had no effect on cumulative emissions or emissions standardized by BW or HCW for the other four gases (P ≥ 0.268). LUB is a novel tool to reduce emissions of NH3 gas per kilogram of unshrunk live BW and hot carcass weight.

中文翻译：

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在育成期的最后 3 个月，饲喂 lubabegron 对饲养在环境监测小围栏中的肉牛的气体排放、生长性能和胴体特征的影响

在维持或提高食用动物生产效率的同时促进环境管理的技术的发展对于生产食品供应以满足不断增长的人口需求的可持续性至关重要。因此，Elanco (Greenfield, IN) 寻求选择性 β-调节剂 (lubabegron; LUB) 的环境适应症。LUB 最近获得美国食品和药物管理局 (FDA) 的批准，可在饲喂期的最后 14 至 91 天饲喂饲养场牛，以减少气体排放/kg 未收缩的最终 BW 和 HCW。使用剂量（基于 0.0、1.38、5.5 或 22.0 mg·kg-1 DM）和性别（公牛或小母牛）因素的 4 × 2 因子处理排列。进行了三个 91 天的周期（112 头牛/周期），每个剂量 × 性别组合由一个牛圈围栏（CPE；14 头牛/CPE）代表，总共有 168 头公牛和 168 头小母牛（n = 6 次重复） /剂量）。对于研究中测量的任何变量，没有观察到剂量和性别之间的相互作用（P ≥ 0.063）。根据相对于环境空气的 CPE 浓度，对所有笔评估了五种气体：NH3、CH4、N2O、H2S 和 CO2。饲喂牛 5.5 和 22.0 mg·kg-1 LUB (P ≤ 0.023) 减少了累积 NH3 气体排放，与阴性对照相比，饲喂 1.38 mg·kg-1 LUB 的牛趋于降低 (P = 0.076) ( CON）。与 CON 相比，所有 LUB 剂量的累积 NH3 气体排放减少 960 至 1032 g，加上 HCW 增加 15 至 16 kg（P ≤ 0.019），导致所有三种 LUB 处理的 NH3 气体排放量/kg HCW 减少（P ≤ 0.004）。与 HCW 类似，对于所有 LUB 剂量，NH3 气体排放量/kg 未收缩的最终 BW 均有所减少（P ≤ 0.009），这归因于 NH3 气体排放量的减少和 BW 的数值增加。剂量对其他四种气体的累积排放量或 BW 或 HCW 标准化排放量没有影响（P ≥ 0.268）。LUB 是一种新颖的工具，可减少每公斤未收缩的活 BW 和热胴体重量的 NH3 气体排放量。剂量对其他四种气体的累积排放量或 BW 或 HCW 标准化排放量没有影响（P ≥ 0.268）。LUB 是一种新颖的工具，可减少每公斤未收缩的活 BW 和热胴体重量的 NH3 气体排放量。剂量对其他四种气体的累积排放量或 BW 或 HCW 标准化排放量没有影响（P ≥ 0.268）。LUB 是一种新颖的工具，可减少每公斤未收缩的活 BW 和热胴体重量的 NH3 气体排放量。