I know exactly what you mean, alfabeet is pelleted alfalfa and sugarbeet mixed. It is perfectly healthy as a hay replacement. Regularly used by vet hospitals because it is fibre but it is highly palletable. Reccomended by vets as a hay replacement for old ponies with no teeth and reccomended by the veteran horse society. Reccomended by the lami trust as a bulk feed for ponies who can't go out on grass due to lammi.
I do know one 51 yearold pony who for the last 10 years has been unable to eat anything if it wasnt a mush. He was fed pretty much only alfabeet or grass pellets soaked into a mush, no hay as he couldnt chew it, no haylege for the same reason. He continued to be a brilliant family friend and taugh 6 generations of the same family to ride. Last time I saw him last year he was still doing leadrein PC.
This is alfabeet:
Alfa Beet - Dengie Horse Feeds