What do you recommend to feed a 2-3 year old? And why?

I have a 2 year old appendix filly. Looking for a different feed so I'd love to hear what you like/dislike, any advice welcome! Tia! 

For a young growing horse you need to have a total protein level of 15% to 16% for the entire diet. Since roughage is, or should be, the largest part of the diet, any additional nutritional support should keep that in mind. If your hay or pasture is very poor in quality, this would be a good place for a ration balancer since they typically are around 30% protein and can help boost the total dietary protein up to the required level. If your hay quality is good, a ration balancer would not be the answer, and a grain replacer like Renew Gold (you know I would have to say that) or stabilized Rice Bran can be used to keep disruptive grain based feed out of the system. This allows for a far more normal gut function and proper growth. 

I feed western alfalfa to all my crew from the get go. There is precious little nutritional gap - just the higher calcium that I offset with beet pulp shreds, Renew Gold, and sunflower heart and chips. My weaners have nibbled this with their mommas and that is continued as they grow up. I have raised some really nice sized babies on this regime. The weaners/yearlings/two year olds get more actually than my retired stallion, and the broodmare gets his amount when she's not pregnant or nursing. The most I feed is 2 lb per day RG/1 lb bp shreds/3-4 oz sf heart and chips. My 'bagged' feed for horses now costs less per horse than my chicken feed!! Of course, the alfalfa is $$$.

It depends on exercise level and current body weight.