Every year I am asked about the nutritional value of feedstuffs and each year Beef Magazine provides a feed composition table in either on-line form or as a downloadable PDF file. 

This table provides 280 commonly used cattle feedstuffs and their nutritional breakdown; however, keep in mind that feed composition is not constant and vary for any number of reasons.  While an actual analysis is always best when balancing rations, the table provided will at least get you in the ball park.

Hopefully this will help you in providing your cattle a balanced ration.