Mum rang tack shop (I think!) and we said we had a 'fiery' pony who fizzes up on anything with molasses or sugar in it, and they recommended Happy Hoof!
Why do you need to feed chaff? If essential then why not just make your own out of good quality hay? Would be a lot cheaper too!
I use to love making chaff, although can't see the point of feeding it myself, but making chaff with Simon Bates in the background, now I'm showing my age!
We use to have a chaffing machine, oh how would I describe it...a funnel that you put the hay in that narrows at the bottom with a couple of blades operated by a hand wheel. I suppose the nearest thing to one nowadays would be a garden shredder, that might do the job, although they are about £80 you might save a fortune long run - and they would be electric now so easy peasie.
We used to have to do it years ago, it didn't take that long; a bit like the chainsaw massacre if we were in a hurry though but would either do the daily amount or if we had time, do the whole week's worth all at once - probably with Radio Caroline on too which is even older than Simon Bates!