*4.2. Sample Collection*

In total 476 fresh fecal samples were collected randomly from Bactrian camels grouped into 16 herds located at 16 collection sites in Xinjiang, from July 2016 to September 2019 (Figure 1). Each herd contained between 30 and 300 Bactrian camels. The Bactrian camels were free grazing in desert and semi-desert areas, so their age could not be accurately divided. In some of these areas, cattle, sheep, and horses in pastures also grazed freely. The Bactrian camels had access to pastures or areas where cattle, sheep, and horses had grazed. For each animal, the fresh fecal sample was collected from the ground immediately after defecation, and only one sample was collected per animal into a plastic container that was marked with the sample number and site. After shipping to the laboratory in a cool condition, the fecal samples were stored at 4 ◦C prior to DNA extraction.
