This report reviews the history of antibiotic growth promoters (AGPs) in animal agriculture, the concerns about antimicrobial resistance, and the regulatory responses in the European Union and the United States. It highlights the experience in Denmark, where AGPs were banned in 1995, and the subsequent reduction in antimicrobial usage and changes in animal performance. The biological basis for the effects of antibiotics on animal growth efficiency is discussed, focusing on their impact on intestinal microbiota and host animals. The report also explores the challenges of finding suitable replacements for AGPs and the need for a multifaceted approach to maintain animal productivity. The global trend towards reducing AGP use and the importance of risk assessment and surveillance are emphasized.This report reviews the history of antibiotic growth promoters (AGPs) in animal agriculture, the concerns about antimicrobial resistance, and the regulatory responses in the European Union and the United States. It highlights the experience in Denmark, where AGPs were banned in 1995, and the subsequent reduction in antimicrobial usage and changes in animal performance. The biological basis for the effects of antibiotics on animal growth efficiency is discussed, focusing on their impact on intestinal microbiota and host animals. The report also explores the challenges of finding suitable replacements for AGPs and the need for a multifaceted approach to maintain animal productivity. The global trend towards reducing AGP use and the importance of risk assessment and surveillance are emphasized.