Research Note: Integrated gut microbiome and short-chain fatty acids responds to dominance hierarchy in roosters

The dominant chickens have priority over the use of resources, such as resting places and the announcement of dawn. While cooperation from the subdominant animal is of great help to reduce conflict and maintain the sustainability of a group. However, whether the dominance hierarchy is associated with individuals’ health is not yet known. In this study, we first determined the dominance hierarchy within a group of roosters, to figure out its effects on individuals’ health status by the determination of microbial composition and short-chain fatty acids (SCFAs). Sixteen Weining roosters were kept in a group in order to fix and determine the ranking of dominance hierarchy, as R1 (the highest-ranking rooster), R2, R3, and R4. Results show that the R1 roosters had the highest aggression behavior followed by R2, R3 and R4 (P < 0.05). The alpha diversity of R1, R2, and R4 was higher than R3 roosters (P < 0.05). There were several top 10 phylum and genus microbes among the different ranking roosters (P < 0.05). The acetic acid, propionic acid, butyric acid, and valerate acid concentrations were higher, while isobutyric acid concentration was lower in the higher rank roosters (R1 and R2) than the lower rank roosters, respectively (R3 and R4) (P < 0.05). Our results show that the variation of dominance hierarchy contributes to changes of microbial composition, diversity and metabolites. Dominant roosters seem to benefit from SCFAs activities while subdominant roosters profit from microbial functions.