Thank you for taking the time to do the numbers, Chris.  That is about what I've seen...there is a lot of feed value in a few acres of corn silage, both in cow-days and quality/energy content. The silage also lets you use grassier hay along with it.

What I have not seen is your $63/ton (~$45/large round bale) for your local good hay, at least any time in the past couple years. 

Checking the Dyersville 8/27 hay auction "good" quality large rounds were $85-$140/ton even right now at the peak of hay production and trough of prices. They have been much higher. Need to add trucking.

Jim

I should know better than respond to some posters.