Rearing system causes changes of behavior, microbiome, and gene expression of chickens

ABSTRACT It has been long demonstrated that cage rearing (CR) deprives the animal of the possibility to express natural behaviors and results in stress. However, the effect of the rearing system on gene expression and the molecular levels of the gut microbiome are unknown. 10-wk-old Beijing You chickens were studied in parallel CR and free-range (FR) systems for 30 wk, to investigate the effect of rearing systems on behavior, microbiota composition, and gene expression. From week 40, a match-mismatch design was conducted for 5 wk. The results indicated that CR deprives the animals of natural behaviors, evidenced by sham dust-bathing behavior. A decreased alpha diversity of gut microbiome composition of CR chickens was seen in FR compared to CR-FR chickens (P