# Fecal steroids, short-chain fatty acids, and microbiota in high- versus low-yielding forest musk deer

## TL;DR

This study compares high- and low-yielding forest musk deer to understand how gut hormones, fatty acids, and microbes affect musk secretion.

## Contribution

The study identifies specific gut microbiota and metabolites linked to musk secretion in forest musk deer.

## Key findings

- High-yielding deer had higher testosterone, estradiol, and cortisol levels compared to low-yielding deer.
- Low-yielding deer showed higher butyrate and hexanoate levels, which correlated inversely with steroid hormones.
- Certain gut microbes like Ruminococcaceae UCG-014 were strongly associated with musk secretion and steroid metabolism.

## Abstract

Adult male forest musk deer (Moschus berezovskii; FMD) possess high medicinal and economic value due to their musk secretion capacity. However, under farming conditions, a subset of individuals exhibit abnormal musk secretion or complete secretory failure, resulting in economic losses. This phenomenon is associated with lipid metabolism and gut microbiota alterations. We compared fecal steroid hormones, short-chain fatty acids (SCFAs), and bacterial communities between high-yielding and low-yielding FMD under identical captive conditions. Seven male FMD (2 ~ 6 years old) secreting normal musk comprised the high-yielding group (HFMD), while seven age-matched males secreting abnormal musk formed the low-yielding group (LFMD). Results showed significantly higher concentrations of testosterone (T), estradiol (E2), cortisol, and corticosterone (CORT) in HFMD versus LFMD group (p < 0.05). Conversely, SCFA levels showed an inverse pattern: butyrate and hexanoate concentrations were significantly higher in LFMD group (p < 0.05). Following multiple testing correction, the relative abundances of Fibrobacteres (p = 0.013; FDR = 0.170), Tenericutes (p = 0.013; FDR = 0.107), and Verrucomicrobia (p = 0.037; FDR = 0.223) were observed to be significantly higher in the HFMD group compared to the LFMD group. Furthermore, distinct microbial biomarkers were identified between the two groups. Certainly, ASV_849 (taxonomically classified as Ruminococcaceae UCG-014) exhibited significant correlations with multiple steroid hormones and SCFAs (p < 0.05; FDR = 0.246). Moreover, correlation analysis demonstrated positive associations between musk secretion and E2, T, cortisol, and CORT (p < 0.05), but negative correlations with hexanoate (p < 0.05). Butyrate and hexanoate were inversely correlated with T (p < 0.05). These findings reveal that the gut microbiota may regulate musk secretion through their metabolites (SCFAs), which not only play a key mediating role in microbe-host interactions but may also indirectly influence the process of musk secretion via their interplay with steroid metabolism. This study provides valuable insights into the captive care management of adult male FMD and strategies for enhancing musk secretion.

The online version contains supplementary material available at 10.1186/s13568-025-01967-6.