This book gives a comprehensive account of the methodologies for measuring methane from in vitro fermentation systems, and from stall-fed and grazing animals. The chapters have been contributed by experts in the field and methods and protocols have been presented in simple format for direct practical use. A variety of techniques for measuring methane emissions ranging from radio and stable isotopic methods, respiration chambers to the tunnel method and sulphur hexafluoride tracer technique, which can be used with animals in the field have been covered. In vitro fermentation systems which provide the opportunity to test new plants for their potential to reduce methane emissions and to help design new management and feeding strategies based on these measurements also form the subject of this book. This book will equip the readers to measure and monitor methane emissions accurately and to meet the challenge of improving productivity from ruminants without damaging the environment. The techniques and procedures described are also relevant and adaptable to other anaerobic systems such as biogas plants, manure storage and application systems, sludge systems, etc.