The objective of the current study was to evaluate the effects of tannin and monensin supplementation in feedlot diets and breed (Holstein vs. Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics. Eighty purebred Holstein calves (HOL; initial body weight (BW) = 130 ± 5 kg) and eighty Angus × Holstein calves (AXH; initial BW = 129 ± 6 kg) were blocked by initial BW and randomly assigned to 40 pens. Dietary treatments consisted of a steam-flaked corn-based diet supplemented with 1) no feed additive (CON); 2) 30 mg of monensin/ kg of dry matter (DM) (MON; Rumensin 90, Elanco, Greenfield, IN); 3) 1.5 g tannin)/ kg of DM (TAN; ByPro, 70% condensed tannin, SilvaFeed, Indunor, S.A., Buenos Aires, Argentina); 4) M+T, the combination of MON plus TAN dietary treatments. Data were analyzed as a randomized complete block in a 2 x 4 factorial arrangement of treatments, using pens as experimental units. There were no interactions (P > 0.05) between feed additives and breed. Supplemental MON increased (P ≤ 0.04) initial 112-day BW and gain efficiency. However, there were no dietary treatment effects (P > 0.10) on overall growth performance. Monensin supplementation decreased (P = 0.04) minimum daily ruminal temperature compared with other dietary treatments during July, but TAN did not affect ruminal temperature. Holstein steers had greater (P = 0.04) overall DM intake compared with AXH, with no difference (P = 0.19) in overall ADG, leading to increased (P < 0.01) gain efficiency for AXH compared with HOL. Dietary net energy for maintenance and gain, based on growth performance, were greater (P ≤ 0.01) for AXH vs HOL. Compared with HOL, AXH steers had greater (P ≤ 0.01) carcass weight, dressing percentage, kidney, pelvic, and heart fat, 12th rib fat thickness, longissimus area, and preliminary yield grade. Holstein steers had lower (P ≤ 0.04) minimum average ruminal temperature during June compared with AXH, with no differences (P ≥ 0.14) between breeds during July or August. Results indicate that feed additives did not appreciably affect steer growth performance and carcass characteristics, but crossbred AXH steers had greater growth performance, efficiency of dietary energy utilization, and carcass quality measures compared with HOL. This study observed a reduction (4.7%) in maintenance energy expenditure in AXH compared with HOL, implying in maintenance energy coefficient of 0.086 vs 0.082 for HOL and AXH, respectively.

中文翻译：

---

低水平单宁补充对荷斯坦和安格斯 x 荷斯坦交叉饲喂浓缩精育日粮 328 天比较生长性能的影响

本研究的目的是评估饲养场日粮和品种（荷斯坦与安格斯×荷斯坦）中补充单宁和莫能菌素对生长性能、能量效率和胴体特性的影响。将 80 头纯种荷斯坦犊牛 (HOL；初始体重 (BW) = 130 ± 5 kg) 和 80 头安格斯 × 荷斯坦犊牛 (AXH；初始 BW = 129 ± 6 kg) 按初始 BW 进行分组，并随机分配到 40 个栏。饮食治疗包括以蒸汽压片玉米为基础的饮食，辅以 1) 无饲料添加剂 (CON)； 2) 30 mg 莫能菌素/kg 干物质 (DM) (MON; Rumensin 90, Elanco, Greenfield, IN)； 3) 1.5克单宁)/千克DM(TAN；ByPro，70％缩合单宁，SilvaFeed，Indunor，SA，布宜诺斯艾利斯，阿根廷)； 4）M+T，MON加TAN饮食治疗的组合。使用栏作为实验单位，以 2 x 4 因子排列的处理方式将数据作为随机完整组进行分析。饲料添加剂与品种之间不存在交互作用（P>0.05）。补充 MON 增加了 (P ≤ 0.04) 初始 112 天的体重和增益效率。然而，饮食治疗对整体生长性能没有影响（P>0.10）。 7 月份，与其他饮食治疗相比，补充莫能菌素降低了每日最低瘤胃温度 (P = 0.04)，但 TAN 并不影响瘤胃温度。与 AXH 相比，荷斯坦阉公牛的总体 DM 摄入量更高（P = 0.04），而总体 ADG 没有差异（P = 0.19），导致 AXH 的增重效率比 HOL 更高（P < 0.01）。根据生长表现，AXH 与 HOL 相比，用于维持和增重的膳食净能更大 (P ≤ 0.01)。与 HOL 相比，AXH 阉牛的胴体重量、屠宰率、肾脏、骨盆和心脏脂肪、第 12 肋骨脂肪厚度、最长肌面积和初步产量等级均较高（P ≤ 0.01）。与 AXH 相比，荷斯坦公牛 6 月的最低平均瘤胃温度较低 (P ≤ 0.04)，而 7 月或 8 月品种之间没有差异 (P ≥ 0.14)。结果表明，饲料添加剂不会明显影响阉牛生长性能和胴体特性，但与 HOL 相比，杂交 AXH 阉牛具有更高的生长性能、日粮能量利用效率和胴体质量指标。这项研究观察到，与 HOL 相比，AXH 的维持能量消耗减少了 (4.7%)，这意味着 HOL 和 AXH 的维持能量系数分别为 0.086 和 0.082。