Vegetables and Colour

Not long ago I had a friend tell me about what she fed her horses and one of the things she would feed was pumpkin( I think it was pumpkin?) for her chestnut she said it brang out a really nice colour on him.
She also said different veges for different colours should be fed but she wasn't sure of which.
Does anyone do this, Does it work? What veges for what colour? Cook or raw? You know, the 21 questions...

Just to put it out there... erm... no it dosen't work this way. Sounds like an old wives tale.

Sunflower seeds, oats, paprika all help with horse's coats... but the horse dosen't have to 'match' color.