The productivity potential of our livestock has not been fully exploited because of deficit feed resources and under-utilization of available improved technologies. For getting high productivity from livestock at economic rate, it is essential to enhance the feeding value of available feed resources. To provide better nutrition to fast growing animal population, it was realized that these fibrous crop residues must be used in such a way that could provide required amount of energy, protein and mineral to the animals at a desired level. The supplementation of probiotics (bacteria/fungi/yeast) has recently been reported to improve nutritional status and to provide therapeutic benefits to ruminants. The use of Lactobacillus acidophilus or other lactic acid producing bacteria as dietary supplement are known to create environment to enhance digestion and to stimulate immunity. The authors have tried to carry out the research work on feeding of probiotics with or without urea-ammonia treated wheat straw on nutrient utilization in growing crossbred males. This book will be useful to the students, farm managers, field workers, dairy administrators, planners and enlightened farmers.