Here's a little insight to those fodder supplements:
Corn & Rye: both are low in regard to nutrition, but they will make your feed last longer when mixed, corn also serves as a great treat.
Kudzu: It is a good source of protein being in fact a legume, I think it's something like 18% protein by dry weight.
Legumes: This obviously includes plants with peas/pods and is a very good source of protein. They are also rich in iron and vitamin B.
Bahia Grass: Like any other grass serves as a good treat and source of greens.
All have their pros and cons.