Identifying indirect selection traits for residual feed intake in broilers: roles of behavior, chronic stress, and digestive development

Improving feed efficiency (FE) is essential for reducing broiler production costs, and residual feed intake (RFI) serves as a key indicator for evaluating FE in livestock. Fast‐growing yellow‐feathered broilers retain the characteristic appearance of yellow‐feathered chickens while demonstrating superior FE. However, research on the FE of this breed remains limited. This study focuses on Jinling Hua chickens, a fast‐growing yellow‐feathered broiler breed. Feed intake (FI) data were collected from 36 to 49 days of age, and behavioral states were recorded simultaneously. The results revealed that birds housed in the middle of the poultry house exhibited significantly more sleep and feeding/drinking behaviors than those in other locations, and also had significantly lower RFI ( P < 0.05). Correlation analysis indicated that behavioral state score was positively correlated with body weight gain (BWG) ( P < 0.01, r = 0.066) and negatively correlated with feed conversion ratio (FCR) ( P < 0.01, r = −0.068). Feather follicle corticosterone concentration (FFCC) was significantly higher in the low-RFI birds than in the high-RFI birds ( P < 0.05). FFCC was positively correlated with BWG ( P <0.01, r = 0.423) and negatively correlated with both RFI and FCR ( P < 0.01, r = −0.357, −0.374). Significant differences were also observed in duodenal villus length, villus-to-crypt (V/C) ratio, and intestinal radius between the two groups ( P <0.01). These findings suggest that cage position influences RFI and behavior in fast-growing yellow-feathered broilers, and that RFI is associated with FFCC and duodenal development. This study provides a theoretical basis for identifying indirect selection traits for RFI in this breed.