Effects of lubabegron fumarate on ruminal fermentation and microbial community in a rumen simulation system.

Introduction: The expansion of the global beef industry intensifies concerns regarding ammonia emissions, posing a significant challenge to environmental sustainability and production efficiency. Lubabegron fumarate (LBF), a novel Methods: Using a rumen simulation system, we evaluated the effects of LBF on fermentation parameters, nutrient digestibility, and urease activity. To elucidate the underlying mechanisms, an integrated multi-omics approach was employed to characterise shifts in microbial community structure, functional potential, and metabolic output, with a specific focus on nitrogen-cycling microbiota. Results: LBF did not directly inhibit urease. Instead, it optimised the rumen microenvironment by increasing total volatile fatty acids and pH, while reducing ammonia nitrogen (NH₃-N) and enhancing starch digestibility. Crucially, LBF orchestrated a selective enrichment of key taxa (e.g., Discussion: LBF reshaped the rumen microecosystem to synchronise carbohydrate fermentation and nitrogen assimilation, thereby optimising nutrient capture and reducing nitrogen waste. These findings provide a mechanistic basis for the strategic application of LBF as a pharmaceutical intervention to improve nitrogen efficiency and mitigate ammonia emissions in cattle production.