What a wind fall! With 1500 lbs. of spent grains I would consider both hogs and mushrooms.
Where I live the market demand for pork has taken a big downturn for feeders and breeders but mushrooms are always going to
sell, especially if you grow some of the big restaurant desirables such as Shitake, Chanterelle, Crimini, and Oysters.
Cattle would take more space per paddock than hogs but hogs need to be moved more often, so take that into account when deciding on beef or pork.
Mushrooms take very little space for large quantities but they do require some special conditions for a commercial operation to succeed.
Redhawk
(I raise AGH and am getting ready to move into
chickens, ducks and mushrooms for sale)