Microorganisms in the rumen play a crucial role in determining the most efficient utilization rate of nutrients. Among these microorganisms, stands out as one of the most representative bacteria within the rumen biological system. is a common strict anaerobic bacterium that is found in the gastrointestinal tract of livestock. plays a crucial role in breaking down and metabolizing complex nutrients like cellulose and protein during food digestion. Moreover, it is capable of working together with other bacteria in the body's digestive system. Several studies have shown a strong correlation between the abundance of and livestock growth performance. This paper provides a comprehensive review of the current research on the function, mechanisms, and applications of in the gastrointestinal tract. The insights provided in this review could serve as a theoretical basis for accurately classifying further investigating its effects and potential mechanisms on livestock growth performance, and exploring its practical applications.