Yup, Herd is a good name, there are many other companies that import an Italian model & slap their name on it. (I just got one at a consignment auction, hope to use it this coming week.....) If you go to the Worksaver web page you can find an on-line manual, get an idea of what they will do.
Most are in the 500 lb size, and will spread many small seeds, as well as some spreading fertilizer & lime.
You are money ahead to get a model with an agitator to keep the fertilizer flowing if that is the bulk of your work. Fert & especially lime like to 'bridge' over the openning & stop flowing.
If you need bigger, there are pto powered trailers that han handle up to several tons of fertilizer. Let us know what scale you are looking for.
--->Paul