4. Discussion
4.1 Diversity of the gut microbiota of wild and captive R. brelichi
The living environment of wild animals is mainly caused by environmental changes (captive breeding or semi-release, etc.) caused by the protection of species characteristics, which affect the gut microbial composition of wild animals to a certain extent, especially endangered wild animals (Zeng, 2020). Multiple studies have shown that the richness and diversity of the gut microbiota were reduced to varying degrees after captivity in Macaca fascicularis (Sawaswong et al., 2021),Moschus berezovskii (Li et al., 2017), R. roxellanae (Zhao et al., 2023), and Ailuropoda melanoleuca (Cheng et al., 2020), with some of the natural flora potentially being lost. In this study, the gut microbial richness and diversity of captive R. brelichi were significantly higher than those of wild R. brelichi , which was consistent with the results of a previous study of captive and wildR. roxellanae by Wang et al. (2023). As a typical leaf-eating primate, R. brelichi has access to a more uniform diet in the wild but a richer range of food in captivity, including leaves from a variety of trees, as well as a range of fruits, vegetables, and sources of protein. We believe that this factor may be an important explanation for the richer and more diverse gut microbiota of captive R. brelichi (Campbell et al., 2020). In addition, captive breeding limits the roaming and foraging behaviors of R. brelichi , and increases their close contact with each other and with humans. It is speculated that captivity increases the likelihood of the transmission of intestinal microbiota through oral and fecal routes, and potentially pathogenic microorganisms may be more abundant in the gut microbiota ofR. brelichi in captivity.
4.2 Composition and difference of gut microbiota in wild and captive