Once a horse reaches 2 years old it's feed/nutritional requirements are the same as an adult horse, I would just be feeding hay when in, grass when out and a handful of something like fast fibre with a good general supplement (I really like equimins tip top). Fed at the RDA for an adult, not a youngster.
I agree with queenbee ( assuming your horse is up to weight etc) just a handful of feed ( fast fibre or unmolassed chaff) with a vit/min supplement should be all you need. I personally really rate equimins and I use the advance complete which does my horses very well.
A lot of people I know feed a small amount of nuts etc but its not providing their nutritional requirements, so to me a good vitamin supplement is vital
Thanks, I really didn't think she needed any more than what I'd feed my older 2 but after her breeder saying what she did, I was worried I'd stunt her growth of something! I feed hifi lite and top spec lite, a complete feed, fed with the hifi to bulk it up but they are on good grass 24/7.
You get a lot of growth problems from over feeding, far far more then under feeding in my mind. To many people chuck feed into their horses for no need.