Terrific if you have a horse like mine that is adversley affected by spring grass (she literally explodes out of her back end ) The speedi-beet helps to keep a regular level in her stomach and she has had solid faeces all the time since adding it to her feeding regime. She literally has half a cup (dry) soaked twice a day. (I also feed her Biotal equine gold year round too).
Also, its good for adding more fibre to their diet and masking supplements and any medication they may have.
It's also a good way of getting extra moisture in their feed, even the fussiest eaters seem to love it.