Feed efficiency is one of the economically important traits for the cattle industry that affects profit (feed costs) and the environment (production of manure and methane). Due to that feed efficiency is driven by multi-factors, mechanisms contributing to the animal to animal variation in this trait have not been well defined, limiting the development of precision feeding strategies to improve the herd production efficiency. Rumen microbial fermentation and volatile fatty acids (VFA) production have been recently reported to be associated with cattle feed efficiency, however the roles of rumen epithelial function in feed efficiency are less studied although the rumen epithelium has an important function in VFA absorption and metabolism which can affect host feed efficiency. Rumen epithelium is colonized with a diverse microbial population, termed epimural microbiota, which has proposed functions in tissue development, barrier and inflammation, urea transport, and oxygen scavenging, suggesting that they can affect rumen epithelial functions and subsequently cattle feed efficiency. Especially, prospective functions of epimural microbiota, enhanced rumen immunity and increased rumen epithelial thickness, might contribute to less nutritional requirement for tissue recuperation. Thus, the understanding of the functions of rumen epithelium, epimural microbiota, and rumen epithelial host-microbe interactions is essential to identify their roles in contributing to feed efficiency. In this review, we will focus on to date research findings on the structure of rumen epithelium, epimural microbiota, and epithelial host-microbe interactions together with their functions and how these are associated with feed efficiency, aiming to provide insights on future directions to study rumen epithelial host-microbe interactions and improve the rumen functions in cattle.

饲料效率是养牛业的重要经济特征之一，影响利润（饲料成本）和环境（粪便和甲烷的生产）。由于饲料效率是由多种因素驱动的，导致动物之间这一性状变异的机制尚未明确，限制了精准饲喂策略的发展，以提高畜群生产效率。最近有报道称，瘤胃微生物发酵和挥发性脂肪酸（VFA）的产生与牛饲料效率有关，然而，尽管瘤胃上皮在VFA吸收和代谢中具有重要功能，但瘤胃上皮功能在饲料效率中的作用研究较少。会影响宿主的饲料效率。瘤胃上皮定植有多种微生物群，称为壁外微生物群，其在组织发育、屏障和炎症、尿素运输和氧清除方面具有功能，表明它们可以影响瘤胃上皮功能，从而影响牛的饲料效率。特别是，壁外微生物群的预期功能、增强的瘤胃免疫力和增加的瘤胃上皮厚度，可能有助于减少组织恢复的营养需求。因此，了解瘤胃上皮、壁外微生物群和瘤胃上皮宿主-微生物相互作用的功能对于确定它们在提高饲料效率中的作用至关重要。 在这篇综述中，我们将重点关注迄今为止关于瘤胃上皮结构、壁外微生物群和上皮宿主-微生物相互作用及其功能以及它们与饲料效率的关系的研究结果，旨在为未来的研究方向提供见解瘤胃上皮宿主-微生物相互作用并改善牛的瘤胃功能。