Rising feed costs in the poultry industry have the greatest impact on the price of the final product. To address this issue, several indicators have been developed to assess feed efficiency. One such indicator is residual feed intake (RFI) which represents the difference between actual and expected feed consumption. A lower RFI indicates better performance, making it a valuable trait for sustainable poultry production. RFI is influenced by several factors, including metabolism, body temperature regulation, arrangement of feathers, behavior and physical activity, all of which affect energy expenditure. The trait has moderate heritability, enabling genetic improvement through selective breeding. Accurate calculation of RFI is essential for effective selection, taking into account growth and maintenance needs. Understanding these factors enables breeders to increase feed efficiency, reduce production costs and promote sustainability within the industry.