Potassium carbonate improves milk quality by enhancing rumen metabolism

Mid-lactation represents a critical phase in dairy production, characterized by sustained high milk yields and significant metabolic stress in dairy cows. Dietary supplementation with potassium carbonate has emerged as a promising strategy to enhance milk quality, yet its specific mechanisms of action, particularly regarding the relationship between rumen microbiome alterations and production performance, remain poorly understood. To address this knowledge gap, we conducted a randomized complete block trial involving 60 multiparous Holstein cows of similar parity. To elucidate the underlying mechanisms of these observed effects, we conducted comprehensive sequencing analyses of the rumen microbiota and metabolome. These advanced analyses revealed significant alterations in microbial community structure and function, particularly in pathways related to nutrient metabolism. Notably, we identified increased KEGG gene abundance associated with two critical metabolic pathways: the biosynthesis of amino acids and the biosynthesis of long-chain fatty acids. These findings suggest that potassium carbonate supplementation may enhance milk quality by modulating microbial metabolic capabilities in the rumen. Our results demonstrate that supplementation with 500 g/day/head of potassium carbonate (MD group) represents the most effective strategy for enhancing milk quality through targeted modulation of rumen microbiota and metabolites. This study provides novel insights into how rumen microbiome composition and function respond to varying levels of potassium carbonate supplementation. The identification of production performance-correlated microbial changes establishes a foundation for future targeted microbiome interventions aimed at optimizing dairy cow production and milk quality. These findings have important implications for developing precision nutrition strategies in dairy production systems.