I've had some success using Elmer's wood glue in the cracks, then immediately dry sanding. The loose antler chips and dust get packed into the glue filled cracks. When it's done, it looks pretty good. Try it on some smaller junk and see how it turns out. Don't over-do it, or you'll smooth out all the ridges and bumps, and that wouldn't look right.
By the way, that "WILD ANTLER MAGIC" is terrific stuff. I've used it and recommend it completely. I wish I could make it to the Antler Fest tomorrow, I would like to get my hands on some of the lighter color for desert muleys.