My girls love the norm, apples etc. Faith will bend over backwards for a pair, she makes a great big dribbly mess though
I had a friend who fed one horse betroot to enhance her colour, she was a black/brown with tan at her flanks. The tan bits went a funky reddish colour.
A lady I used to ride for fed her pally pumpkin, again to enhance colour. The horse went from pale to a rich golden colour and looked great.