Comparative Analysis of Gut Microbiota and Metabolome of Captive Male Malayan Pangolins with Normal and Abnormal Reproduction

Ex-situ conservation and captive breeding are important measures for protecting endangered species. However, captive conditions inhibit reproduction in some wild animals, especially males. Under captive conditions, which differentially expressed microbiota and metabolites significantly influence or are key to reproductive performance? This study aimed to investigate the effects of differentially expressed microbiota and metabolites on reproductive performance, including male Malayan pangolins with normal reproductive behavior (NR, with natural mating behavior) and those with abnormal reproductive behavior (AR, without natural mating behavior). Five male Malayan pangolins with normal reproductive behavior and eight with abnormal reproductive behavior were divided into NR and AR groups. Fresh fecal samples were collected for metagenomic and metabolomic analysis. The results showed that Bacillota, Pseudomonadota, Bacteroidota, Actinomycetota, and Fusobacteriota were the dominant phyla. <i>Escherichia</i>, <i>Lactobacillus</i>, <i>Lactococcus</i>, <i>Limosilactobacillus</i>, and <i>Ligilactobacillus</i> were the dominant genera. The abundance of <i>Absiella</i>, <i>Butyribacter</i>, and <i>Candidatus Scatovivens</i> in the gut of the NR group was significantly higher than in the AR group (<i>p</i> < 0.05), while the abundance of <i>Clostridium</i>, <i>Mycoplasmopsis</i>, and <i>Facklamia</i> in the gut of the AR group was significantly higher than in the NR group. A total of 94 differentially expressed metabolites were identified, with Argininosuccinic acid and Cortol significantly upregulated in the AR group, and gamma-Aminobutyric acid and gamma-Glutamylglutamic acid significantly downregulated. These microbiota and metabolites can be screened as potential key biomarkers that might influence the reproductive performance of male pangolins. These findings provide important insights into the husbandry and management of captive pangolins and other endangered wild animals.