Garcia Florencia, Muñoz Camila, Martínez-Ferrer Jorge, Urrutia Natalie L, Martínez Emilio D, Saldivia Marcelo, Immig Irmgard, Kindermann Maik, Walker Nicola, Ungerfeld Emilio M
Universidad Nacional de Córdoba, Facultad de Ciencias Agropecuarias, Departamento de Producción Animal, Ing Agr. Félix Aldo Marrone 746, Córdoba Capital, Córdoba, 5001, Argentina.
Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación Remehue, Ruta 5 km 8 norte, Osorno, Los Lagos, 5290000, Chile.
Heliyon. 2022 Jun 16;8(6):e09738. doi: 10.1016/j.heliyon.2022.e09738. eCollection 2022 Jun.
Methane is a potent but short-lived greenhouse gas targeted for short-term amelioration of climate change, with enteric methane emitted by ruminants being the most important anthropogenic source of methane. Ruminant production also releases nitrogen to the environment, resulting in groundwater pollution and emissions of greenhouse gas nitrous oxide. We hypothesized that inhibiting rumen methanogenesis in dairy cows with chemical inhibitor 3-nitrooxypropanol (3-NOP) would redirect metabolic hydrogen towards synthesis of microbial amino acids. Our objective was to investigate the effects of 3-NOP on methane emissions, rumen fermentation and nitrogen metabolism of dairy cows fed true protein or urea as nitrogen sources. Eight ruminally-cannulated cows were fed a plant protein or a urea-containing diet during a Control experimental period followed by a methanogenesis inhibition period with 3-NOP supplementation. All diets were unintentionally deficient in nitrogen, and diets supplemented with 3-NOP had higher fiber than diets fed in the Control period. Higher dietary fiber content in the 3-NOP period would be expected to cause higher methane emissions; however, methane emissions adjusted by dry matter and digested organic matter intake were 54% lower with 3-NOP supplementation. Also, despite of the more fibrous diet, 3-NOP shifted rumen fermentation from acetate to propionate. The post-feeding rumen ammonium peak was substantially lower in the 3-NOP period, although that did not translate into greater rumen microbial protein production nor lesser nitrogen excretion in urine. Presumably, because all diets resulted in low rumen ammonium, and intake of digestible organic matter was lower in the 3-NOP period compared to the Control period, the synthesis of microbial amino acids was limited by nitrogen and energy, precluding the evaluation of our hypothesis. Supplementation with 3-NOP was highly effective at decreasing methane emissions with a lower quality diet, both with true protein and urea as nitrogen sources.
甲烷是一种强效但寿命短暂的温室气体，是短期缓解气候变化的目标对象，反刍动物排放的肠道甲烷是最重要的人为甲烷来源。反刍动物生产还会向环境中释放氮，导致地下水污染和温室气体氧化亚氮排放。我们假设，用化学抑制剂3-硝基氧丙醇（3-NOP）抑制奶牛瘤胃甲烷生成会使代谢氢转向微生物氨基酸的合成。我们的目标是研究3-NOP对以真蛋白或尿素作为氮源的奶牛甲烷排放、瘤胃发酵和氮代谢的影响。八头装有瘤胃瘘管的奶牛在对照实验期饲喂植物蛋白或含尿素日粮，随后进入添加3-NOP的甲烷生成抑制期。所有日粮均无意缺氮，添加3-NOP的日粮比对照期日粮的纤维含量更高。预计3-NOP期较高的日粮纤维含量会导致更高的甲烷排放；然而，添加3-NOP后，按干物质和消化有机物摄入量调整后的甲烷排放量降低了54%。此外，尽管日粮纤维含量更高，但3-NOP使瘤胃发酵从乙酸盐转向丙酸盐。3-NOP期采食后瘤胃铵峰值显著降低，尽管这并未转化为更高的瘤胃微生物蛋白产量，也未减少尿液中的氮排泄。据推测，由于所有日粮导致瘤胃铵含量较低，且3-NOP期可消化有机物摄入量低于对照期，微生物氨基酸的合成受到氮和能量的限制，从而无法对我们的假设进行评估。无论是以真蛋白还是尿素作为氮源，添加3-NOP在低质量日粮条件下对降低甲烷排放都非常有效。
