A rugged life: how host-microbiome adaptations associated with the semi-feral lifestyle of gayal (Bos frontalis).

The semi-domesticated gayal (Bos frontalis) is an endangered browsing ruminant inhabiting the rugged Eastern Himalayan foothills, and maintains an energy-intensive lifestyle on nutrient-poor, fiber-rich feed. However, the dietary, microbial, and host physiological features underlying this adaptation remain poorly understood. Here, we analyzed fecal metagenomes from ten bovine populations (n = 334) to characterize dietary composition. Then we profiled the four-chambered (FC) stomach microbiome in adult gayal (Bos frontalis), yak (Bos grunniens), and taurine cattle (Bos taurus). Host transcriptomes were profiled across the FC stomach in adult individuals from gayal, yak and cattle. Dietary analysis revealed a woody plant-dominated, bamboo-rich dietary pattern in gayal. Gastric metagenomes in gayal showed high population-level microbial diversity, pronounced individual-associated community structure, and functional potentials related to aromatic compound transformation, nitrogen metabolism, and metabolic flexibility. Transcriptomes revealed compartment-specific specialization in the gayal stomach, including rumen immune signatures and reticulum contractile/electrophysiological features. Exploratory compartment-level integration further suggested possible consistency between host transcriptomic features and microbial functional potential. Together, these multi-omics findings suggest a host-microbiome system potentially associated with the utilization of chemically complex, low-quality forage, providing a framework for understanding digestive features of browsing ruminants and for conserving host-associated gastrointestinal microbiomes.