In this book poultry diseases that are directly related to the gastrointestinal tract, as well as diseases that are not directly, but that could be influenced by, the intestinal health are covered. In addition, the impact of human pathogens harboured by poultry is also discussed. As a background to understanding the covered topics, basic insights in poultry anatomy, physiology and immunology are given. The book also contains pictures that aid in the description of poultry anatomy, digestive physiology and poultry diseases.