Feed intake is one of the determinants of livestock productivity. Theoretically, feed intake of ruminants can be predicted from component of ingestive behaviour. Accordingly, recording ingestive and feeding behaviour is crucial because of its implication to feeding management strategies. An accurate methodology and a novel-sensing device have been developed and explored using sheep as an experimental animal-model. Based on this study, novel and principal components of ingestive behaviors such as prehensability, masticability, swallowbility, and bolus formation budget have been established. From those components, then, the “ingestion event” has been determined as the “basic unit of eating”. In the future, this parameter must theoretically and practically be considered and explored more in investigating the ingestive and ruminative behaviours of ruminants reared both in confinement and free-ranging conditions. This book is important to be referenced by scientist in animal agriculture and veterinary sciences, plant-forages breeder, and practitioners who are concerned in the developments of the domestic and wild ruminants as well as other potential herbivores.