Signatures of the wild: seasonal variation of microbiome and diet in the mountain roaming semi-domesticated mithun, Bos frontalis

Mithun ( Bos frontalis ) is a semi-domesticated bovine native to the montane forests of the Eastern Himalayas, where it holds deep cultural significance, but its ecology is poorly understood. To better understand how mithun interact with their environment, we used metabarcoding to track their diet and the bacterial component of the rumen microbiome across four seasons over one year. We also compared the mithun microbiome to sympatric free-grazing yellow cattle to test whether their rumen bacterial communities were distinct and more seasonally sensitive. Because no local plant DNA reference library existed, we developed an ethnobiologically informed database using local ecological knowledge to identify plant taxa in the diet. The mithun microbiome was distinct and more variable across seasons than that of the local yellow cattle. Furthermore, mithun microbiome composition and predicted function shifted seasonally in ways that both tracked and diverged from dietary changes, indicating that diet and microbiome are not always synchronized. These findings reveal that mithun harbor a distinct, environmentally responsive microbiome reflective of their semi-wild ecology and forest-based diet.