Integrative analysis of gut microbiota and plasma metabolites reveals mechanisms underlying aggressive behavior in chronically stressed broiler chickens

Chronic stress in livestock production affects animal welfare and productivity, often leading to aggressive behavior in broiler chickens. We exposed broiler chickens to chronic corticosterone to simulate stress and compared them to controls, evaluating production performance, hypothalamic serotonin levels, cecal microbiota, plasma metabolites, and aggression. In this study, broiler chickens were divided into two groups following corticosterone injection: the control group (CON) and the chronic corticosterone exposure group (CORT). Stressed chickens showed reduced growth, lower hypothalamic serotonin, and increased aggression. Gut microbiota changes included increased Clostridium and decreased Actinomycetales and Coriobacteriaceae , correlating with aggression. Plasma metabolomics revealed that indole and O-acetylcarnitine. butyryl-lcarnitine, 6-hydroxydaidzein, guanidinoacetate, d-fructose, (R)-4-hydroxymandelate, biochanin A, 26-hydroxyecdysone and L-tryptophanwere positively associated with aggression, while kaempferol niacinamide, indican, pyroglutamic acid, 2,4-dinitrophenol, salicylic acid and leucodopachrome were negatively associated. These findings suggest that gut microbiota and plasma metabolites mediate stress-induced aggression in broiler chickens, providing potential targets for managing behavior in stressed poultry.