Li Bin, Jia Gaobin, Wen Dongxu, Zhao Xiuxin, Zhang Junxing, Xu Qing, Zhao Xialing, Jiang Nan, Liu Zhenjiang, Wang Yachun
Institute of Animal Husbandry and Veterinary, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa, China.
Agricultural College, Ningxia University, Yinchuan, China.
Front Microbiol. 2022 Oct 10;13:1027138. doi: 10.3389/fmicb.2022.1027138. eCollection 2022.
The grassland in the Qinghai-Tibetan plateau provide habitat for many indigenous and introduced ruminants which perform important ecological functions that impact the whole Qinghai-Tibetan plateau ecosystem. These indigenous Tibetan ruminants have evolved several adaptive traits to withstand the severe environmental conditions, especially cold, low oxygen partial pressure, high altitude, strong UV radiation, and poor forage availability on the alpine rangelands. Despite the challenges to husbandry associated with the need for enhanced adaptation, several domesticated ruminants have also been successfully introduced to the alpine pasture regions to survive in the harsh environment. For ruminants, these challenging conditions affect not only the host, but also their commensal microbiota, especially the diversity and composition of the rumen microbiota; multiple studies have described tripartite interactions among host-environment-rumen microbiota. Thus, there are significant benefits to understanding the role of rumen microbiota in the indigenous and introduced ruminants of the Qinghai-Tibetan plateau, which has co-evolved with the host to ensure the availability of specific metabolic functions required for host survival, health, growth, and development. In this report, we systemically reviewed the dynamics of rumen microbiota in both indigenous and introduced ruminants (including gut microbiota of wild ruminants) as well as their structure, functions, and interactions with changing environmental conditions, especially low food availability, that enable survival at high altitudes. We summarized that three predominant driving factors including increased VFA production, enhanced fiber degradation, and lower methane production as indicators of higher efficiency energy harvest and nutrient utilization by microbiota that can sustain the host during nutrient deficit. These cumulative studies suggested alteration of rumen microbiota structure and functional taxa with genes that encode cellulolytic enzymes to potentially enhance nutrient and energy harvesting in response to low quality and quantity forage and cold environment. Future progress toward understanding ruminant adaptation to high altitudes will require the integration of phenotypic data with multi-omics analyses to identify host-microbiota co-evolutionary adaptations enabling survival on the Qinghai-Tibetan plateau.
青藏高原的草原为许多本地和引进的反刍动物提供了栖息地，这些反刍动物发挥着重要的生态功能，影响着整个青藏高原生态系统。这些本地的藏系反刍动物已经进化出了几种适应性特征，以抵御恶劣的环境条件，特别是寒冷、低氧分压、高海拔、强紫外线辐射以及高山牧场饲料供应不足的情况。尽管由于需要增强适应性给养殖带来了挑战，但仍有几种驯化的反刍动物被成功引入到高寒牧区，在恶劣环境中生存下来。对于反刍动物来说，这些具有挑战性的条件不仅影响宿主，还影响其共生微生物群，特别是瘤胃微生物群的多样性和组成；多项研究描述了宿主 - 环境 - 瘤胃微生物群之间的三方相互作用。因此，了解瘤胃微生物群在与宿主共同进化以确保宿主生存、健康、生长和发育所需的特定代谢功能方面的作用具有重大意义。在本报告中，我们系统地综述了本地和引进反刍动物（包括野生反刍动物的肠道微生物群）瘤胃微生物群的动态变化，以及它们的结构、功能，以及与不断变化的环境条件（特别是低食物供应）的相互作用，正是这些环境条件使得反刍动物能够在高海拔地区生存。我们总结出三个主要驱动因素，包括挥发性脂肪酸产量增加、纤维降解增强和甲烷产量降低，这些因素表明微生物群在营养缺乏期间能够维持宿主生存的更高效率的能量收获和营养利用。这些累积研究表明，瘤胃微生物群结构和功能类群会随着编码纤维素酶的基因发生改变，以潜在地增强营养和能量获取，从而应对低质量和低数量的饲料以及寒冷环境。未来在理解反刍动物对高海拔地区适应性方面取得进展，将需要整合表型数据与多组学分析，以识别宿主 - 微生物群共同进化的适应性特征，从而使反刍动物能够在青藏高原生存。
