The RFI is independent of growth traits and selecting individuals with low RFI can improve feed efficiency without affecting the laying performance and egg quality of hens. In this study it was found that under similar egg production rates hens in the HRFI group had lower nutrient digestion capacity disrupted lipid metabolism and lower feed utilization efficiency than those in the LRFI group. Further research and validation are needed to investigate the effects of AST HDL-C and ACTH on feed efficiency in the late laying period through serum biochemical index analysis. Through multiomics analysis genes such as ADCY2 ADCY8 CCKAR ACSS2 FABP1 and FABP4 and metabolites such as LysoPI(18:2(9Z,12Z)/0:0) were identified as key genes and biomarkers related to RFI in laying hens during the late laying period. These findings are important for developing strategies to improve feed efficiency in Rhode Island Red pure-line chickens during the late laying period. Additionally in-depth investigations such as histological observations enzyme activity analysis and integration of multiomics techniques are needed to unravel the physiological and biochemical mechanisms of digestive organs that impact feed utilization efficiency in poultry.