Durmic Zoey, Duin Evert C, Bannink André, Belanche Alejandro, Carbone Vincenzo, Carro M Dolores, Crüsemann Max, Fievez Veerle, Garcia Florencia, Hristov Alex, Joch Miroslav, Martinez-Fernandez Gonzalo, Muetzel Stefan, Ungerfeld Emilio M, Wang Min, Yáñez-Ruiz David R
School of Agriculture and Environment, The University of Western Australia, Crawley, WA, 6009, Australia.
Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849.
J Dairy Sci. 2025 Jan;108(1):302-321. doi: 10.3168/jds.2024-25045.
Despite the increasing interest in developing antimethanogenic additives to reduce enteric methane (CH) emissions and the extensive research conducted over the last decades, the global livestock industry has a very limited number of antimethanogenic feed additives (AMFA) available that can deliver substantial reduction, and they have generally not reached the market yet. This work provides technical recommendations and guidelines for conducting tests intended to screen the potential to reduce, directly or indirectly, enteric CH of compounds before they can be further assessed in in vivo conditions. The steps involved in this work cover the discovery, isolation, and identification of compounds capable of affecting CH production by rumen microbes, followed by in vitro laboratory testing of potential candidates. The finding of new bioactive compounds as AMFA can be based on 2 approaches: empirical and mechanistic. The empirical approach involves obtaining and screening compounds present in databases and repositories that potentially possess the desired effect but have not yet been tested, screening natural sources of secondary compounds such as plants, fungi, and algae for their antimethanogenic effects, or examining compounds with antimethanogenic effect on microbes in other research domains outside the rumen. In contrast, the mechanistic approach is the theoretical process of discovery new bioactive compounds based on existing knowledge of a biological target or process. The in vitro methodologies reviewed include examining effects at the subcellular level, in single pure cultures of methanogens and examining in more complex mixed rumen microbial populations. Simple in vitro methodologies (subcellular assessments and batch culture) allow testing a large number of compounds, whereas more complex systems simulating the rumen microbial ecosystem can test a limited number of candidates but provide better insight about the antimethanogenic efficacy. This work collated the main advantages, limitations, and technical recommendations associated with each step and methodology use during the identification and screening of AMFA candidates.
尽管人们对开发抗产甲烷添加剂以减少肠道甲烷（CH）排放的兴趣日益浓厚，且在过去几十年中进行了广泛研究，但全球畜牧业可用的能大幅减少甲烷排放的抗产甲烷饲料添加剂（AMFA）数量非常有限，而且它们通常尚未进入市场。这项工作提供了技术建议和指导方针，用于开展旨在筛选化合物在体内条件下进一步评估之前直接或间接减少肠道CH潜力的测试。这项工作涉及的步骤包括发现、分离和鉴定能够影响瘤胃微生物甲烷生成的化合物，随后对潜在候选物进行体外实验室测试。发现作为AMFA的新生物活性化合物可基于两种方法：经验性方法和机理性方法。经验性方法包括获取和筛选数据库及储存库中可能具有所需效果但尚未经过测试的化合物，筛选次生化合物的天然来源（如植物、真菌和藻类）的抗产甲烷效果，或研究瘤胃以外其他研究领域中对微生物具有抗产甲烷作用的化合物。相比之下，机理性方法是基于对生物靶点或过程的现有知识发现新生物活性化合物的理论过程。所综述的体外方法包括在亚细胞水平进行效应检测、在产甲烷菌的单一纯培养物中进行检测以及在更复杂的瘤胃混合微生物群体中进行检测。简单的体外方法（亚细胞评估和批次培养）能够测试大量化合物，而模拟瘤胃微生物生态系统的更复杂系统能够测试的候选物数量有限，但能更好地洞察抗产甲烷功效。这项工作整理了在鉴定和筛选AMFA候选物过程中与每个步骤及方法使用相关的主要优点、局限性和技术建议。
