Deficiency of Natural Plant-Derived Gut Metabolites Is a Potential Cause of Skeletal Deformities in Captive-Bred Green Peafowl (Pavo muticus)

Background: To recover endangered green peafowl (Pavo muticus) populations, China has implemented ex situ conservation programs centered on captive breeding. However, captive-bred individuals frequently suffer from skeletal deformities, creating a critical bottleneck that compromises future wild reintroductions. Results: This study demonstrates that, although green peafowl possess species-specific genes (Igf2 and Ndufs2), they lack specialized allometric development of the cecum, suggesting that dietary disparities might play a more pivotal role in driving skeletal issues than innate intestinal anatomical factors. Specifically, wild peafowl naturally consume plants from the genus Pistacia, whereas captive birds receive a standardized diet dominated by Glycine. Reflecting these dietary disparities, captive-bred individuals exhibit significantly reduced gut levels of metabolites that regulate osteoclast activity, namely quercetin, taurine, urolithin A, and luteolin. Extensive evidence indicates that these specific metabolites directly modulate bone homeostasis during growth, meaning their reduction poses severe physiological risks. Furthermore, the abundance of these specific metabolites is directly modulated by gut bacterial communities, notably the genera Escherichia and Staphylococcus. We also found that dietary composition serves as a robust cue shaping gut microbiome assembly, acting independently of developmental stages. Conclusions: This study suggests that targeted plant supplementation holds promise in restoring the gut ecosystem and mitigating skeletal deformities, highlighting how diet-driven microbiome stewardship could advance the conservation and reintroduction of endangered species like the green peafowl.