The World Association for Animal Production produces this book that is a reference tool for the animal scientific community and for policy makers worldwide. Sixty authors from the six continents contributed with thirty outstanding manuscripts. This volume is the first of a series that will be produced every year. The objective of this project is to establish a reference volume for livestock system and research development, for the use of international organizations, research institutes, policy makers and animal industries, worldwide. This book is particularly interesting for those wanting to get a deeper knowledge on the ""state of the art"" of livestock systems in the six continents. This aspect is illustrated in the first section of the volume, while the second section describes the development of research activities in nineteen specific fields of animal science. Furthermore, the readers will certainly be interested by reading the ""contemporary issues"" manuscripts belonging to the third section. The articles of this section were selected to accomplish the most ""urgent"" topics in animal industry. The volume is also completed with relevant statistics, furnishing information and data in a homogenous and easy to read structure. The changes that have happened in animal industries in the last decades are clearly illustrated in tables and graphics. These data, together with the interpretation of the articles of the previous sections, will render easier the prediction of future scenarios. The World Association for Animal Production produces this book that is a reference tool for the animal scientific community and for policy makers worldwide. Sixty authors from the six continents contributed with thirty outstanding manuscripts.