Diarrhea serves as a vital health indicator for assessing wildlife populations post-reintroduction. Upon release into the wild, wild animals undergo adaptation to diverse habitats and dietary patterns. While such changes prompt adaptive responses in the fecal microbiota, they also render these animals susceptible to gastrointestinal diseases, particularly diarrhea. This study investigates variations in fecal microorganisms and hormone levels between diarrhea-afflicted and healthy Przewalski’s horses. The results demonstrate a significant reduction in the alpha diversity of the fecal bacterial community among diarrheal Przewalski’s horses, accompanied by notable alterations in taxonomic composition. Firmicutes, Proteobacteria, and Bacteroidetes emerge as dominant phyla across all fecal samples, irrespective of health status. However, discernible differences in fecal bacterial abundance are observed between healthy and diarrhea-stricken individuals at the genus level, specifically, a diminished relative abundance of Pseudobutyrivibrio is observed. The majority of the bacteria that facilitate the synthesis of short-chain fatty acids, Christensenellaceae_R_7_group (Christensenellaceae), NK4A214_group (Ruminococcus), Lachnospiraceae_XPB1014_group (Lachnospiraceae), [Eubacterium]_coprostanoligenes_group (Eubacterium), Rikenellaceae_RC9_gut_group, Lachnospiraceae_AC2044_group (Lachnospiraceae), and Prevotellaceae_UcG_001 (Prevotella) are noted in diarrhea-affected Przewalski’s horses, while Erysipelotrichaceae, Phoenicibacter, Candidatus_Saccharimonas (Salmonella), and Mogibacterium are present in significantly increased amounts. Moreover, levels of immunoglobulin IgA and cortisol are significantly elevated in the diarrhea group compared with the non-diarrhea group. Overall, this study underscores substantial shifts in fecal bacterial diversity, abundance, and hormone levels in Przewalski’s horses during episodes of diarrhea.

Wild ungulates play crucial roles in maintaining the structure and function of local ecosystems. The alpine musk deer (Moschus chrysogaste), white-lipped deer (Przewalskium albirostris), and red serow (Capricornis rubidus) are widely distributed throughout the Nyenchen Tanglha Mountains of Tibet. However, research on the mechanisms underlying their coexistence in the same habitat remains lacking. This study aimed to investigate the mechanisms underlying the coexistence of these species based on their dietary preferences through DNA barcoding using the fecal samples of these animals collected from the study area. These species consume a wide variety of food types. Alpine musk deer, white-lipped deer, and red serow consume plants belonging to 74 families and 114 genera, 62 families and 122 genera, and 63 families and 113 genera, respectively. Furthermore, significant differences were observed in the nutritional ecological niche among these species, primarily manifested in the differentiation of food types and selection of food at the genus level. Owing to differences in social behavior, body size, and habitat selection, these three species further expand their differentiation in resource selection, thereby making more efficient use of environmental resources. Our findings indicate these factors are the primary reasons for the stable coexistence of these species.

The alpine musk deer (Moschus chrysogaster) is a critically endangered species in China whose wild populations have precipitously declined due to habitat degradation and poaching. In response, China established the world’s first captive breeding facility for this species in 1990. Despite over three decades of closed breeding, the genetic consequences of long-term captivity remain unclear. Here, we present the first comprehensive assessment of mitochondrial genetic diversity in a captive population of 409 individuals, using three mitochondrial markers (D-loop, Cytb, and COI) and comparative data from wild conspecifics. Our results reveal a pronounced reduction in genetic diversity in the captive population compared to wild populations. Nucleotide diversity (π) and haplotype diversity (Hd) were consistently lower across all markers in captivity, with D-loop Hd = 0.639 and π = 0.01073. Further combined sequence analysis revealed a single dominant haplotype (Hap4) representing 56.99% of individuals, indicative of severe haplotype loss and homogenization. Although some haplotypes are shared with wild populations, captive populations exhibit strong genetic differentiation from wild populations, with the captive populations retaining only a limited fraction of the species’ maternal lineages. This pronounced genetic erosion driven by strong founder effects and genetic drift raises concerns about the viability and reintroduction success of this species. These findings highlight the inherent limitations of closed captive populations in preserving evolutionary potential and adaptive capacity. Our study emphasizes the urgent need for evidence-based genetic management, including founder augmentation and population exchange, to mitigate inbreeding and maintain genetic diversity.

The gut microbial ecosystem is structured by the gut microbiota residing in animal hosts. It plays a critical role in modulating core host physiological functions, covering food digestion, nutrient absorption, energy metabolism and immune regulation. In this study, we performed 16S rDNA high-throughput sequencing to characterize the gut microbiota of wild alpine musk deer (Moschus chrysogaster, AMD) and ex situ conserved forest musk deer (Moschus berezovskii, FMD). We then inferred the putative functional profiles based on known taxon–function relationships. Our analyses revealed no significant difference in gut microbiota alpha diversity between wild AMD and ex situ conserved FMD. However, significant divergence in gut microbiota beta diversity was detected between the two species. The family Muribaculaceae and its unclassified affiliated genus as well as the genus Monoglobus and Pseudomonas were significantly more abundant in wild AMD than in ex situ conserved FMD. By contrast, the genera Prevotellaceae_UCG_004, Alistipes, Christensenellaceae_R-7_group, Akkermansia and the family Oscillospiraceae were significantly more abundant in ex situ conserved FMD than in wild AMD. Furthermore, the Firmicutes/Bacteroidetes ratio was numerically higher in FMD than in AMD. Together, these results indicate that the gut microbiota differences between the two musk deer species are consistent with the dietary factors differences. These findings further suggest that the formulated concentrate diet fed to FMD was lower in fiber and higher in digestible energy than the natural diet of AMD. These dietary factors may partly underlie the observed microbiota differences. Accordingly, we recommend adjusting the feeding regime and husbandry practices for FMD to better match the native food plants consumed by AMD. Such adjustment represents an evidence-based strategy for improving the health of FMD populations.