Metabolic and gut microbial remodeling in captive Amur tigers under uniform feeding

Captive breeding serves as a crucial strategy for preserving the genetic resources of endangered species and achieving population rejuvenation, yet a pervasive reliance potentially compromises its conservation efficacy on standardized nutritional protocols. As a flagship endangered species, captive Amur tigers have been subjected to a unified breeding and management model for an extended period. To better understand the physiological status of Amur tigers, we employed an integrated approach of non-targeted metabolomics and 16 S rRNA sequencing technology to systematically analyze the fecal samples collected from subadult, adult, and old captive Amur tigers under unified feeding conditions. The results indicated that a total of 169 significantly different metabolites (SDMs) were identified across the three groups. The subadult tigers exhibited a significant increase in metabolites associated with membrane lipids. The adult group contained more substances conducive to lipid digestion and absorption, such as bilirubin and taurocholic acid. In contrast, the old group had more metabolites related to inflammation, including oxidative stress products 5-OxoETE and 13,14-dihydro-15-keto-tetranor prostaglandin E2, as well as natural antioxidant molecules like carnosine and L-anserine. Corresponding to the above metabolic characteristics, gut opportunistic pathogens (such as Dysgonomonas , Solobacterium ) were enriched in the old group, whereas potentially beneficial bacteria taxa like Lachnoclostridium were more prevalent in the adult group. Correlation analysis revealed that Lachnoclostridium was significantly negatively correlated with prostaglandin derivatives, in contrast to the positive correlation observed for Solobacterium , hinting that alterations in gut microbiota composition are a plausible link to the regulation of inflammation-related metabolites, thereby affecting the health and aging trajectory of Amur tigers. In summary, our research revealed that, even under an identical diet, the Amur tiger exhibits significant age-specific metabolism and gut microbiota, with greater enrichment of potentially harmful metabolites and microbiota in the old stage. These insights support a shift toward tailored, precision nutrition protocols grounded in life stage biology.