A bibliometric review about scientific trends and advances on residual feed intake (RFI) and feed efficiency in ruminants

The increasing demand for sustainable livestock production systems has intensified scientific interest in feed efficiency traits, particularly residual feed intake (RFI), as a strategy to improve productivity while reducing environmental impacts. This study provides a comprehensive bibliometric assessment of global scientific production on RFI and feed efficiency in ruminants. A total of 2632 documents indexed in Scopus and Web of Science databases between 2015 and 2024 were analyzed, covering 374 scientific sources and involving 8,406 authors. Scientific output showed a strong and consistent upward trend throughout the study period, with an annual growth rate of 48.9%, particularly from 2019 onwards. Brazil, United States, Australia, Canada, and China were identified as the leading contributors to research development in this field. Authorship patterns revealed a highly collaborative research structure, with an average of 6.97 co-authors per publication, reflecting the interdisciplinary nature of feed efficiency studies. Keyword co-occurrence and network analyses highlighted the close integration of RFI research with themes related to sustainability, methane emissions, genetics, nutrition, and rumen biology. Overall, the results indicate that research on RFI has evolved from a predominantly zootechnical indicator toward a consolidated and sustainability-oriented scientific domain, reinforcing its strategic importance for the development of climate-smart ruminant production systems.