Temporal dynamics shifts in multi-kingdom rumen microbiota and fermentation profiles of water buffalo under heat stress

Buffaloes (Bubalus bubalis), widely distributed in tropical and subtropical regions, possess physiological and behavioral adaptations that support heat tolerance and make them vital for food security and rural livelihoods in developing countries. However, climate change–driven increases in heat stress compromise their productivity, reproduction, and health, thereby threatening agricultural sustainability. To address this gap, ten ruminally cannulated buffaloes (Nili-Ravi × Murrah, average body weight 571.2 ± 31.1 kg) were randomly assigned to either a heat stress group or a non-heat stress group, with cooling management applied in the latter. This study specifically investigated the temporal dynamics of rumen microbial community composition in dairy buffaloes during mid-term heat stress exposure lasting approximately 28 days, while exploring interactions among microbial taxa and between microbes and rumen fermentation characteristics. Heat stress significantly reduced the concentrations of propionate, butyrate, and ammonia nitrogen (NH3-N), and altered the profile of volatile fatty acids. These changes were accompanied by notable disruption of microbial diversity and reorganization of microbial interaction networks. Specifically, heat stress weakened the modularity and hub diversity of microbial co-occurrence networks while enhancing their robustness. Key taxa responsive to heat stress included Anaeroplasma, Lentimicrobium, Segatella, Christensenellaceae R-7 group and Pseudobutyrivibrio, which were identified as topologically central nodes in the co-occurrence network. By day 28 of heat stress, the number of differential genera declined and network modularity showed partial convergence, indicating progressive temporal changes in community structure. Heat stress markedly alters rumen fermentation patterns and reshapes microbial community structure in buffaloes, characterized by pronounced initial shifts followed by progressive temporal changes with partial convergence over time. The identification of microbial taxa that were topologically central in the co-occurrence network highlights their potential relevance as targets for nutritional interventions. These findings provide new insights into the dynamic associations between rumen microbes and rumen fermentation parameter profiles under thermal stress, offering a theoretical basis for precision regulation strategies in buffalo production.