Coprophagy Couples Hindgut Fermentation with Multi-Site Microbial Organization in Brandt's Vole.

Coprophagy, the ingestion of feces, is widespread among vertebrates and plays an important role in hindgut-fermenting herbivores by facilitating nutrient recycling and maintaining gut microbial stability. However, most studies have focused on cecal or fecal microbiota, with limited attention to microbial communities at other body sites. Here, we used Brandt's vole, a species exhibiting frequent coprophagic behavior, to examine how coprophagy prevention affects hindgut fermentation and microbial communities across multiple sites, including the tongue, lung, stomach, and cecum. Coprophagy prevention increased food intake but reduced body weight gain and significantly decreased cecal acetate, propionate, and butyrate concentrations. At the microbial level, coprophagy prevention increased the Simpson index of the tongue microbiota and induced modest compositional shifts in the tongue, lung, and stomach microbiota. In contrast, the cecal microbiota exhibited greater compositional and predicted functional changes. Notably, coprophagy prevention reduced the Bray-Curtis distance between tongue and cecal microbiota without altering the number of shared amplicon sequence variants. Together, these findings indicate that coprophagy not only promotes efficient nutrient recycling through hindgut fermentation but may also influence microbiota composition across behaviorally interconnected digestive niches.