Thanks Cobb,
In that case you will need a supplement or some DDGs to go with the hay and silage to get enough protein to support gains.  
I just did a rough ration, and if the hay is 7% protein you could feed the corn silage and balage 50/50 (all they'll eat) plus 5# of DDGs and .5-.75# of a balancer to support 2.25# of daily gain.  Or 50/50 and 2.5# of a 40% supplement for the same gain.