Integrated effects of diet and probiotics on rumen microbiota and host physiology in ruminants

Rumen microbiota is essential for nutrient digestion, immune function, and metabolic health in ruminants. With growing interest in sustainable animal production, recent studies have focused on the combined use of diet and probiotics in modulating rumen microbial community and its association with host performance. This review summarizes the effects of dietary strategies on microbial composition and fermentation efficiency. This review also discusses how probiotics such as <italic>Saccharomyces cerevisiae, Lactobacillus</italic>, <italic>Lacticasibacillus, Lactiplantibacillus</italic>, and <italic>Bacillus</italic> spp. stabilize the rumen environment, enhance fiber degradation, and reduce harmful microbes. These effects are influenced by both the probiotic strain and physiological stage of the animal. Furthermore, it explores how microbial fermentation products, such as volatile fatty acids and ammonia, play an important role as functional indicators reflecting microbial activity and host physiology. Metabolomics, which enables the comprehensive analysis of rumen metabolites, has proven valuable for investigating the influence of diet and probiotics on host metabolism. Hence, the integration of dietary strategies with probiotics can synergistically enhance rumen health and overall productivity in ruminants.