The question is, what are you feeding for?
A token because everyone else is - then some plain hay chop - halleys which is delivered to door, dengie mollases free, mollichop mollases free, top chop lite... The list goes on.
For condition, then as above but with an unmollased beet or micronised linseed.
To be honest though, I would be either stopping the feed altogether or not changing it at all... And I'm fairly sure it would be the first. I would be feeding hay only and it would just be tough if she didn't eat any buckets given. I wouldn't be dabbling with any hay replacers ( graze on or horsehage) I wouldn't even be feeding haylage if i could help it due to the fermentation of it which could upset the gut. I would be removing everything that could upset the gut.
As a note for grass products, interestingly madam can tolerate grass nuts - no idea why! She has a handful of halleys chop with a splatter of liquid grass nuts ( make it very runny).