Schilling-Hazlett Ashley K, Stackhouse-Lawson Kimberly R, Bryant Tony C, Vargas Juan J, Place Sara E, Ritten John P, Martins Edilane C, Souza Willian A, Swenson Maya A, Burke Erin N, Campion Rhyse K, Shadbolt Anna M, Carvalho Pedro H V
CSU AgNext, Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Five Rivers Cattle Feeding, Johnstown, CO 80534, USA.
J Anim Sci. 2025 Sep 24. doi: 10.1093/jas/skaf322.
The objectives of this study were to evaluate the comparative growth performance, carcass characteristics, and gas flux of yearling Bos indicus (BI; Brahman) and Bos taurus (BT; Angus) steers managed with (TRT) and without (CON) the use of growth-promoting technology (GPT). One hundred BI (initial body weight (IBW) = 342 ± 31 kg) and 100 BT (IBW = 341 ± 21 kg) steers were fed for 180d in 2 consecutive phases. In Phase 1, d 0-83, cattle of each sub-species were blocked by body weight and randomly assigned to a management treatment in 10-hd research pens (5 pens/treatment). In Phase 2, d 84-180, cattle were moved and randomly assigned to a 50-hd research pen (1 pen/treatment) equipped with 1 GreenFeed automated head chamber system (C-Lock, Rapid City, SD, USA) and 5 SmartFeed bunk systems (C-Lock, Rapid City, SD, USA) for measuring individual gas flux of methane (CH4), carbon dioxide (CO2), oxygen (O2), and hydrogen (H2) and feed intake, respectively. Data were analyzed with R (R Core Team, 2021, v. 4.4.1) software to assess the fixed effects of cattle sub-species, treatment, and their interaction for growth performance collected in Phase 1 and 2, and gas flux which was only measured in Phase 2. In phase 1, IBW did not differ (P > 0.75) by sub-species or treatment. Dry matter intake (DMI), average daily gain (ADG), and feed efficiency (G:F) were greater (P < 0.01) for BT, resulting in greater final body weight (FBW) for BT compared to BI. Within sub-species, DMI did not differ (P > 0.35) between treatments in Phase 1, but ADG, G:F, and FBW were greater (P < 0.01) for TRT compared to CON. In Phase 2, DMI increased with the use of GPT. However, there was a sub-species × treatment interaction (P ≤ 0.04) where greater increases in ADG and FBW were observed between TRT and CON for BT relative to BI. Furthermore, BI had a greater proportion of Standard and Select quality grades relative to BT. Daily CH4 production (g CH4/d), CH4 yield (g CH4/kg DMI), and yield of CH4 (% of gross energy intake) were less (P < 0.01) for BI than BT. The use of GPT decreased emissions intensity per unit ADG and carcass gain; furthermore, a sub-species × treatment interaction existed (P ≤ 0.05), where a greater decrease in EI was observed between CON and TRT for BT when compared to BI. Ultimately, BT had greater growth performance and carcass quality, but BI emitted less CH4, highlighting the complex tradeoffs resulting from sustainability-related research in beef production systems.
本研究的目的是评估采用（TRT）和不采用（CON）生长促进技术（GPT）管理的一岁印度瘤牛（BI；婆罗门牛）和欧洲牛（BT；安格斯牛）阉牛的生长性能、胴体特征和气体通量的比较情况。100头BI阉牛（初始体重（IBW）=342±31千克）和100头BT阉牛（IBW = 341±21千克）在两个连续阶段饲养180天。在第1阶段，即第0至83天，每个亚种的牛按体重进行分组，并随机分配到10头存栏量的研究栏中接受管理处理（每个处理5个栏）。在第2阶段，即第84至180天，牛被转移并随机分配到一个50头存栏量的研究栏（每个处理1个栏），该栏配备1个GreenFeed自动头部腔室系统（C-Lock，美国南达科他州拉皮德城）和5个SmartFeed料槽系统（C-Lock，美国南达科他州拉皮德城），分别用于测量甲烷（CH4）、二氧化碳（CO2）、氧气（O2）和氢气（H2）的个体气体通量以及采食量。使用R软件（R核心团队，2021年，版本4.4.1）对数据进行分析，以评估牛亚种、处理及其相互作用对第1阶段和第2阶段收集的生长性能以及仅在第2阶段测量的气体通量的固定效应。在第1阶段，IBW在亚种或处理之间没有差异（P>0.75）。BT的干物质采食量（DMI）、平均日增重（ADG）和饲料效率（G:F）更高（P<0.01），导致BT的最终体重（FBW）比BI更大。在亚种内，第1阶段各处理之间的DMI没有差异（P>0.35），但TRT的ADG、G:F和FBW比CON更大（P<0.01）。在第2阶段，DMI随着GPT的使用而增加。然而，存在亚种×处理相互作用（P≤0.04），相对于BI，BT在TRT和CON之间观察到ADG和FBW的增加更大。此外，相对于BT，BI具有更高比例的标准和精选质量等级。BI的每日甲烷产量（克CH4/天）、甲烷产率（克CH4/千克DMI）和甲烷产量（占总能量摄入量的百分比）比BT少（P<0.01）。GPT的使用降低了单位ADG和胴体增重的排放强度；此外，存在亚种×处理相互作用（P≤0.05），与BI相比，BT在CON和TRT之间观察到的排放强度降低更大。最终，BT具有更好的生长性能和胴体品质，但BI排放的CH4较少，这突出了牛肉生产系统中与可持续性相关研究产生的复杂权衡。
