Fat,shiny,and not hot?

I have a six year old mare that is not looking that good at the moment she is rugged and feed a sport pellet at the moment she this mare has been feed a lot of different foods in the past and she is a mare that gets very hot so she has been on just gr for about two month and the horse is now calm when i work her what do i feed her to put on the weight and shine and not make her hot because while she has had a brake from all those feeds she has now become calm thanks anita