Lethbridge Research and Development Center, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada.
DSM Nutritional Products France, Research Center for Animal Nutrition, Saint Louis Cedex, France.
J Anim Sci. 2018 Jun 29;96(7):2923-2938. doi: 10.1093/jas/sky174.
The study objective was to evaluate the combined effects of supplementing monensin (MON) and the methane (CH4) inhibitor 3-nitrooxypropanol (NOP) on enteric CH4 emissions, growth rate, and feed conversion efficiency of backgrounding and finishing beef cattle. Two hundred and forty crossbred steers were used in a 238-d feeding study and fed a backgrounding diet for the first 105 d (backgrounding phase), transition diets for 28 d, followed by a finishing diet for 105 d (finishing phase). Treatments were as follows: 1) control (no additive); 2) MON (monensin supplemented at 33 mg/kg DM; 3) NOP (3-nitrooxypropanol supplemented at 200 mg/kg DM for backgrounding or 125 mg/kg DM for finishing phase); and 4) MONOP (33 mg/kg DM MON supplemented with either 200 mg/kg DM or 125 mg/kg DM NOP). The experiment was a randomized complete block (weight: heavy and light) design with 2 (NOP) × 2 (MON) factorial arrangement of treatments using 24 pens (8 cattle/pen; 6 pens/treatment) at the main feedlot and 8 pens (6 cattle/pen; 2 pens/treatment) at the controlled environment building (CEB) feedlot. Five animals per treatment were moved to chambers for CH4 measurements during both phases. Data were analyzed using a Mixed procedure of SAS with pen as experimental unit (except CH4). Location (Main vs. CEB) had no significant effect and was thus omitted from the final model. Overall, there were few interactions between MON and NOP indicating that the effects of the 2 compounds were independent. When cattle were fed the backgrounding diet, pen DMI was decreased by 7%, whereas gain-to-feed ratio (G:F) was improved by 5% with NOP supplementation (P < 0.01). Similarly, MON improved G:F ratio by 4% (P < 0.01), but without affecting DMI. During the finishing phase, DMI tended (P = 0.06) to decrease by 5% with both MON (5%) and NOP (5%), whereas ADG tended (P = 0.08) to decrease by 3% with MON. Gain-to-feed ratio for finishing cattle was improved with NOP by 3% (P < 0.01); however, no effects were observed with MON. 3-Nitrooxypropanol decreased CH4 yield (g/kg DMI) by 42% and 37% with backgrounding and finishing diets (P ≤ 0.01), respectively, whereas MON did not lower CH4 yield. Overall, these results demonstrate efficacy of NOP in reducing enteric CH4 emissions and subsequently improving feed conversion efficiency in cattle fed high-forage and high-grain diets. Furthermore, effects of NOP did not depend on whether MON was included in the diet.
本研究旨在评估莫能菌素（MON）和甲烷（CH4）抑制剂 3-硝基-1-丙醇（NOP）联合补充对育肥和肥育肉牛肠道 CH4 排放、生长速度和饲料转化率的综合影响。240 头杂交阉牛参与了一项为期 238 天的饲养研究，在最初的 105 天（育肥前期）中喂食育肥前期饲料，28 天为过渡期饲料，然后喂食育肥后期饲料 105 天（育肥后期）。处理如下：1）对照（无添加剂）；2）MON（莫能菌素补充量为 33mg/kg DM；3）NOP（育肥前期补充 200mg/kg DM，育肥后期补充 125mg/kg DM）；和 4）MONOP（33mg/kg DM MON 补充 200mg/kg DM 或 125mg/kg DM NOP）。该实验采用随机完全区组（体重：重和轻）设计，2（NOP）×2（MON）因子处理安排，在主饲料厂使用 24 个畜栏（8 头牛/栏；6 个畜栏/处理），在受控环境建筑（CEB）饲料厂使用 8 个畜栏（6 头牛/栏；2 个畜栏/处理）。在两个阶段，每个处理有 5 头动物被转移到腔室进行 CH4 测量。使用 SAS 的混合程序分析数据，每个畜栏作为实验单位（CH4 除外）。位置（主饲料厂与 CEB）没有显著影响，因此从最终模型中省略。总体而言，MON 和 NOP 之间的相互作用很少，表明这两种化合物的作用是独立的。当牛只喂食育肥前期饲料时，NOP 补充使畜栏干物质采食量（DMI）减少 7%，而增重/饲料比（G:F）提高 5%（P <0.01）。同样，MON 提高 G:F 比 4%（P <0.01），但不影响 DMI。在育肥后期，MON（5%）和 NOP（5%）均使 DMI 趋于减少 5%（P = 0.06），而 ADG 趋于减少 3%（P = 0.08）。NOP 使育肥牛的增重/饲料比提高 3%（P <0.01）；然而，MON 没有产生影响。3-硝基-1-丙醇分别使育肥前期和育肥后期日粮的 CH4 产量（g/kg DMI）降低 42%和 37%（P ≤ 0.01），而 MON 没有降低 CH4 产量。总体而言，这些结果表明 NOP 在减少反刍动物肠道 CH4 排放和提高高纤维和高谷物日粮饲养牛的饲料转化率方面具有功效。此外，NOP 的作用不依赖于日粮中是否包含 MON。
