There's not really any forage that will be a perfect feed by itself; almost any feed you can think of will be over or under in some nutrient(s) if fed by itself.  What a forage test will tell you is what supplements or other feeds will compliment what you have.  Go to the NRC website, and there are many pages of information regarding beef nutrition, as well as plenty of tables to give you age/condition guidelines for putting together a feeding program.