Don't know what you feed or if you just sell the stuff, but we refrain from feeding alfalfa to the horses and mules, as it is way to hot. The protien is too high. Believe it or not, a horse can actually founder if you feed it straight alfalfa.
They want grass hay (New England market) as much for texture as any other reason.
Some does go to dairy cattle or beef and in this climate one makes allowences as a pure grass (Broome,Timothy,Orchard) won`t have good regrowth if it is dry.
A mix of Alfalfa will help with that.
What we do is spread a dose of Urea as fertilizer along with liquid manure from a local dairy farm that grows straight Alfalfa for haylage.
During the summer they can`t spread on that and the corn ground is of course out too.
They need a place to get rid of it and the nitrogen is good for the grasses.
Some Potash is applied as well and Lime if needed.
Soils samples dictate that.