This book is intended to be a companion volume to 'Protein Nutrition in Ruminants' (1982, Academic Press), which emphasized both the role of proteins and new systems for their evaluation. Here the focus is on energy-yielding nutrients and problems involved in evaluating them. Nonetheless in both volumes there is explicit recognition of the interdependence of energy and protein nutrition. I have not attempted to review comprehensively all the literature relating to ruminant energy nutrition and must apologize to colleagues whose work is not fully reported. Where possible tables and figures are...