This book brings together 19 full length manuscripts from invited speakers and nearly 300 abstracts from oral and poster communications presented at the 21st European Symposium on Poultry Nutrition held in Salou/Vila-seca, Spain in May 2017. The invited papers address aspects of poultry nutrition such as feed intake and thermoregulation, feeding strategies and gastrointestinal health, precision feeding (feeding strategies and nutrient requirements), optimized use of feed ingredients, and other hot topics such as updating P requirements of broilers, mycotoxins and future perspectives of poultry production. The open communication abstracts deal with the latest research on poultry nutrition, including feed raw materials, protein sources and amino acids, feed additives and enzymes, nutrition and gut health, mineral nutrition, among other topics.