Rumen microbiome in health and sustainability

• The rumen microbiome, dominated by Bacteroidota and Firmicutes , exhibits conserved core taxa like Prevotella and Ruminococcus , with dynamic shifts influenced by age, diet, and host physiology to optimize nutrient breakdown and VFA production. • Dietary interventions, including fats, amino acids, and phytochemicals, modulate microbial communities to enhance feed efficiency, reduce dysbiosis-linked diseases like ketosis and SARA, and improve ruminant health via targeted metabolic pathways. • Strategies targeting methanogens, such as 3-NOP inhibitors and plant metabolites, effectively mitigate methane emissions by altering rumen archaea and bacteria, promoting sustainable livestock production without compromising performance. The rumen’s microbial community is vast and intricate, playing a key role in animal health and eco-friendliness. Drawing from studies over the past five years, we highlight progress in diversity, early community formation, host-microbe links, diet tweaks, and methane reduction strategies. Metagenomics points to a stable core of Bacteroidota and Firmicutes , featuring genera like Prevotella , Butyrivibrio , and Ruminococcus with shared roles across hosts. Succession happens in young animals and during weaning, while functions show adaptability through varied carbohydrate-digesting enzymes. Diets reshape the mix—fats and plant compounds trigger clear changes in structure and activity. Host factors shine through: milk-producing cows boost bugs for fat and protein breakdown, but imbalances fuel issues like ketosis or acidosis. For cutting emissions, methanogens are prime targets. Overall, this microbiome is tunable via smart feeding and fixes to boost output and curb pollution.