You know how rice expands after it's been boiled in water? Beet pulp does the same thing. That's why some places ban tossing rice at weddings-- when the birds eat it, it expands in their stomachs and can kill them. So even though you don't HAVE to soak it (my mom fed her horse dry beet pulp for a week before we did some research and she was fine), it would probably be a good idea to soak it, just for safety. It might not hurt to feed it dry, but the complications could be disastrous (and costly) if it is.