Broody behavior is regulated by hypothalamic prolactin secretion, which seriously affects egg production in poulty production.  Numerous studies have provided evidence that animal behavior is governed by dynamic bidirectional communication between specific gut bacteria and their host via the brain–gut–microbiome axis.  However, little research focused on how the gut microbiota influence broody behavior in poultry.  In this study, Zhedong white geese in laying and brooding phases were selected.  Ten differentially abundant bacteria in cecum were detected between brooding and laying geese through metagenomic analyses and 16S rRNA sequencing (P<0.05), and Bacteroides fragilis was specifically identified as a key driver species in the brooding geese.  Moverover, the serum metabolites were quantified, and the 313 differentially abundant metabolites were found between the two groups of different physiological geese.  They were primarily enriched in the tryptophan metabolism pathways.  Pearson correlation analyses revealed there was a significant positive correlation between B. fragilis abundance and the context of 11 tryptophan metabolism-related metabolites (such as serotonin, etc.) in broody geese, which hinted that those tryptophan metabolites might be produced or driven by B. fragilis.  Finally, the serum hormone levels were also measured.  We found there was a positive correlation between B. fragilis abundance and content of serotonin.  Besides, prolactin secreted by the pituitary gland was greater in brooding geese than that in laying geese, which was also highly correlated with B. fragilis abundance.  This result implied that B. fragilis could promote the secretion of prolactin by the pituitary gland.  Together, the current study findings provided the information on gut microbiota influencing broody behavior, B. fragilis produced or driven more serum serotonin, and stimulated the pituitary gland to secret more prolactin, which potentially offered a new enlightenment for the intervention of broody behavior in poultry.

Salmonella Enteritidis (SE) is a zoonotic and vertically transmitted pathogen, often colonized in the reproductive tract of adult poultry, which can result in direct contamination of eggs and threaten human health.  Previous studies have revealed that some pattern recognition receptors and resistance genes were involved in regulating immune responses to SE invasion in birds.  However, the role of these immune response genes was not independent, and the interactions among the genes remained to be further investigated.  In this study, SE burden and colonization were determined in reproductive tissue after the ducks were SE-infected, and RNA-sequencing was performed to construct co-expression networks by weighted gene co-expression network analysis (WGCNA).  The result showed that SE could be isolated from 22% of infected-birds in any segment of the reproductive tract and the SE was readily colonized in the stroma, small follicle, isthmus, and vagina of the reproductive tracts in morbid ducks.  The top central, highly connected genes were subsequently identified three specific modules in the above four tissues at the defined cut-offs (P<0.01), including 60 new candidate regulators and 125 transcription factors.  Moreover, those 185 differentially expressed genes (DEGs) in these modules were co-expressed.  Moreover, the hub genes (TRAF3, CXCR4 and IL13RA1) were identified to act with many other genes through immune response pathways including NF-kappaB, Toll-like receptor, steroid biosynthesis, and p53 signaling pathways.  These data provide references that will understand the immune regulatory relationships during SE infection, but also assist in the breeding of SE-resistant lines through potential biomarkers.