I'm feeding two very old horses who struggle to keep on weight.
They get a pelleted feed, a corn/oat/barley mix, and a half pound of beet pulp. It is really working for them.
When I go to feed, I get the two tubs for the oldsters, put their half pound of beet pulp in them and add about a quart (a little more) of hot water. I let those soak while I mix feed for the others and put theirs out.
When I come back I add the senior's mix to the moistened beet pulp, stir and feed them.
I bring the hot water in heavy insulated jugs. If I'm going to be gone, I leave hot water in the jugs and a helper mixes as I do. Amazingly, even in our subzero temps, the water stays warm for 8-10 hours in an unheated shop. I've tried it when I'm around to be sure.
Sometimes there is extra water, but it does not adversely affect the other feeds to be mix with it.