The productive performance of livestock is very low which may be due to non-availability of quality feeds and fodder around the year. There are many methods by which quality of the fodders can be enhanced but important advances have been made in livestock nutrition especially in respect of the role of rumen microorganisms in synthesis of protein from non-protein nitrogen sources such as urea and ammonium compounds. However, the urea can be utilized more efficiently in presence of sulphur and energy sources. The authors have tried to carry out the research work to study the effect of feeding urea treated wheat straw with or without sulphur source on feed utilization by crossbred heifers. The book is primarily aimed at providing comprehensive basic and applied technical information on urea and sulphur supplementation to ruminants. It would be useful book for students, teachers, researchers, planners and enlightened farmers to find out their respective sphere of action on urea and sulphur supplementation.