I use a thing called redi-grass! It is dried grass, and feed about a bucket in total a day because are grass is that bad at the moment slowly weaning them off it. I think its suitable for most horses and ponies as long as feed approiatly. A lot of people use it when grass is bad, and when they horses need the vitamans from somewere else
Love it - has the same (or practically the same) protien and calcium levels as Alfalfa but without any fizziness, very good for fussy feeders who need to put weight on - it is nothing but pure dried grass.
I use Graze On Gold which is suitable for lamintics. My lot love it and it is the only chaff that my very fussy Icelandic will eat. He has Cushings and is therefore prone to lamintis and I have to be ultra careful that he doesn't get anything with molasses in it. He happily eats Graze On gold whereas he refuses Dengie Hi Fi Lite, Alfa A Lite, Readigrass or similar. It is much, much cheaper than Dengie as well which is a bonus!