Air quality is a major factor in intensive livestock management because air is the main vehicle for the dissemination of physical, chemical, and biological agents that affect the health and welfare of animals and humans. Ammonia is the main gaseous pollutant generated in poultry production. In this study, a literature review was conducted to highlight each nitrogen transformation stage during poultry production, while explaining the conversion mechanisms from the ingestion of crude protein to nitrogen volatilization into the atmosphere as ammonia gas. In summary, the steps for the synthesis of uric acid and the excretion of poultry, mineralization of nitrogen present in excreta, and volatilization of ammonia from litter are presented. Based on this review, the importance of understanding the sources and processes involved in ammonia generation and emission in poultry production is clear, thereby allowing the adoption of assertive measures that could minimize negative effects caused by ammonia emission.