Does this horse the quarter horse eat hay?

All horses can eat hay but whether they should or not and how depends on their environment i.e if they live in a stall, or in a field, or both, the climate, etc. the amount of work they are doing, and their weight. This is incorrect. ALL horses NEED to eat hay as the base of their diet (unless they are out on a pasture where they can eat lots of fresh grass). They may or may not need grain based on the factors this person listed (climate, workload, whether the horse is an "easy keeper" or not).