That's kind of an interesting question. I've never heard of forage kochia but the plant we call kochia is a weed you might have heard of...it's what grows up and dies then becomes a tumble weed. We've got it all over SD and I suppose it has some food value the only good thing I can say about it is that we like weeds (Kochia) for bedding areas and pheasants love them. Nobody here would ever think of planting it though. Don't know how similar the forage variety is.
The main reason to plant it is to battle cheatgrass and create a fire barrier. Unless your rainfall is less than 13" or so annual, there is little reason to plant it as a food plot.
Since I do have a cheatgrass problem, I spoke to the local Ag extension agent about it and he recommended against it because it's pretty weedy itself and may displace desirable native species.
You can buy it at Great Basin Seed. http://greatbasinseeds.com/cms-display/splash.html
smsmith, I grew up in the sandy Todd County area near Browerville and grew alfalfa with great success. I spent many of my childhood days trapping gophers for the neighboring dairy farmers and later farming for them. They always planted alfalfa in the spring with peas and oats as a cover crop. Chopped the peas and oats in June for the silo and had a fabulous stand of alfalfa for years to come. The deer gravitated towards those oats and peas and later alfalfa fields. I shot many of my first deer in the Eagle River bottom adjacent to lush alfalfa fields. I think I would do that. . . IMO. If it ain't broke. . .
I do not have any experience with this Kochia that you speak of. It sounds interesting. I have however seen the invasive kind and how nasty it can be.