Institute of Animal Nutrition, Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Brunswick, Germany.
Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
Arch Anim Nutr. 2021 Apr;75(2):79-104. doi: 10.1080/1745039X.2021.1877986. Epub 2021 Mar 1.
The climate-relevant enteric methane (CH) formation represents a loss of feed energy that is potentially meaningful for energetically undersupplied peripartal dairy cows. Higher concentrate feed proportions (CFP) are known to reduce CH emissions in cows. The same applies to the feed additive 3-nitrooxypropanol (3-NOP), albeit through different mechanisms. It was hypothesised that the hydrogen not utilised for CH formation through the inhibition by 3-NOP would be sequestered by propionate formation triggered by higher CFP so that it could thereby give rise to a synergistically reduced CH emission. In a 2 × 2-factorial design, low (LC) or high (HC) CFP were either tested without supplements (CON, CON) or combined with 3-NOP (NOP, 48.4 mg/kg dry matter (DM); NOP, 51.2 mg 3-NOP/kg DM). These four rations were fed to a total of 55 Holstein cows from d 28 until d 120 . DM intake (DMI) was not affected by 3-NOP but increased with CFP (CFP; < 0.001). CH/DMI and CH/energy-corrected milk (ECM) were mitigated by 3-NOP (23% NOP, 33% NOP) ( < 0.001) and high CFP (12% CON, 22% 3-NOP groups) (CFP × TIME < 0.001). Under the conditions of the present experiment, the CH emissions of NOP increased to the level of the CON groups from week 8 until the end of trial (3-NOP × CFP × TIME; < 0.01). CO yield decreased by 3-NOP and high CFP (3-NOP × CFP; < 0.001). The reduced body weight loss and feed efficiency in HC groups paralleled a more positive energy balance being most obvious in NOP (3-NOP × CFP; < 0.001). ECM was lower for NOP compared to CON (3-NOP × CFP; < 0.05), whereas LC groups did not differ. A decreased fat to protein ratio was observed in HC groups and, until week 6 , in NOP. Milk lactose and urea increased by 3-NOP (3-NOP; < 0.05). 3-NOP and high CFP changed rumen fermentation to a more propionic-metabolic profile (3-NOP; CFP; < 0.01) but did not affect rumen pH. In conclusion, CH emission was synergistically reduced when high CFP was combined with 3-NOP while the CH mitigating 3-NOP effect decreased with progressing time when the supplement was added to the high-forage ration. The nature of these interactions needs to be clarified.
肠道甲烷（CH）的形成与气候有关，代表了饲料能量的损失，这对于围产期奶牛能量供应不足的情况可能具有重要意义。已知高比例的浓缩饲料（CFP）可以减少奶牛的 CH 排放。同样适用于饲料添加剂 3-硝基氧基丙醇（3-NOP），尽管其作用机制不同。假设通过 3-NOP 抑制 CH 形成而未被利用的氢会通过高 CFP 触发的丙酸盐形成而被隔离，从而导致 CH 排放的协同减少。在 2×2 因子设计中，低（LC）或高（HC）CFP 要么在没有补充剂的情况下进行测试（CON，CON），要么与 3-NOP 组合（NOP，48.4 毫克/千克干物质（DM）；NOP，51.2 毫克 3-NOP/千克 DM）。这四种日粮共喂给 55 头荷斯坦奶牛，从 d28 到 d120 。3-NOP 对 DM 摄入量（DMI）没有影响，但随着 CFP 的增加而增加（CFP；<0.001）。CH/DMI 和 CH/能量校正乳（ECM）通过 3-NOP（23% NOP，33% NOP）（<0.001）和高 CFP（12% CON，22% 3-NOP 组）（CFP×TIME <0.001）得到缓解。在本实验条件下，从第 8 周开始，NOP 的 CH 排放量增加到 CON 组的水平，并持续到试验结束（3-NOP×CFP×TIME；<0.01）。CO 产量因 3-NOP 和高 CFP 而减少（3-NOP×CFP；<0.001）。HC 组的体重减轻和饲料效率降低与更积极的能量平衡平行，在 NOP 中最为明显（3-NOP×CFP；<0.001）。与 CON 相比，NOP 的 ECM 较低（3-NOP×CFP；<0.05），而 LC 组则没有差异。HC 组和 NOP 组在第 6 周前观察到脂肪-蛋白质比例降低。牛奶中乳糖和尿素因 3-NOP 而增加（3-NOP；<0.05）。3-NOP 和高 CFP 将瘤胃发酵转变为更丙酸代谢的模式（3-NOP；CFP；<0.01），但不影响瘤胃 pH。总之，当高 CFP 与 3-NOP 结合使用时，CH 排放会协同减少，而当补充剂添加到高纤维日粮中时，3-NOP 缓解 CH 的作用会随着时间的推移而降低。需要澄清这些相互作用的性质。
