Thermal manipulation during egg incubation in broiler chickens: A scientometric analysis

Embryonic thermal manipulation (TM) is a promising strategy to mitigate the adverse effects of heat stress on poultry productivity. The aim of this study was to provide a scientometric analysis of the current literature on embryonic TM in broilers, indicating trends, geographic distribution, influential authors, and multidisciplinary links, aiming to provide a comprehensive overview. A search was carried out in December 2024 on Scopus, PubMed, Scielo, and Web of Science using the keywords ("thermal manipulation" OR "temperature manipulation" OR "temperature control" OR "incubation temperature") AND ("incubation" OR "embryo" OR "fetal development") AND broiler. No date restrictions or filters were applied. Only articles that evaluated the TM of embryonated eggs from broilers were selected. Using a dataset of 195 publications from 1994 to 2024, the data were analyzed with Bibliometrix and VOSviewer tools. A sharp increase in scientific output was observed in the last decade, with 71 % of studies published after 2015. Actual central themes include thermotolerance, heat stress, performance, and hatchability. Emerging themes include gene expression, antioxidant, immune response, and acute heat stress. Nine main research networks were identified, with limited interconnection. The United States, Brazil, and Turkey were identified as the main countries, and São Paulo State University, Jordan University of Science and Technology, and Wageningen University are the main research institutions. This study shows how TM during egg incubation has become important in broilers and how it can help them handle heat stress better. Future research should focus on combining TM with genetic, nutritional, and environmental strategies to make the birds more productive and sustainable.