Growth Stages and Inter-Species Gut Microbiota Composition and Function in Captive Red Deer (Cervus elaphus alxaicus) and Blue Sheep (Pseudois nayaur)

SIMPLE SUMMARY: Gut microbiota play a significant role in the diet digestion and health of the host. Many zoos provide research sites for biological scientists to reintroduce animals, especially those facing extinction. Therefore, to prevent the extinction of wild animals, captive wild animals have become one of the ways to protect threatened taxa. Monitoring the structure and function of the gut microbiota of captive animals can help elucidate whether animals have adapted to their artificial environment, which is one of the key issues in wildlife conservation. This study investigated the gut microbiota of blue sheep and red deer at different growth stages and inter-species. The result shows gut microbiota of blue sheep and red deer will change to some extent in different growth stages, but the dominant flora remains stable. In blue sheep and red deer, the gut microbiota differ significantly between species. In addition, several potentially pathogenic microbial communities were identified based on the current findings. The study highlights key gut microbiota across species and ages. ABSTRACT: Blue sheep and red deer, second-class key protected animals in China, are sympatric species with a high degree of overlap of food resources in the Helan Mountains, China. Previous studies with blue sheep and red deer in nature have shown that their physiology is closely related to their gut microbiota. However, growth stages and changes occurring in these species in captivity are still unknown. Thus, 16S rRNA gene sequencing was used to explore diversity, composition and function of the gut microbiota in these two animal species. The diversity and structure of the gut microbiota in captive blue sheep and red deer changed at different growth stages, but the dominant microbiota phyla in the gut microbiota remained stable, which was composed of the phyla Firmicutes, Bacteroidetes and Verrucomicrobia. Moreover, gut microbiota diversity in juvenile blue sheep and red deer was low, with the potential for further colonization. Functional predictions showed differences such as red deer transcription being enriched in adults, and blue sheep adults having a higher cell wall/membrane/envelope biogenesis than juveniles. Microbial changes between blue sheep and red deer at different growth stages and between species mainly depend on the abundance of the microbiota, rather than the increase and absence of the bacterial taxa.