Right now he gets a scoop of oats morning and evening (was fed oats at his previous home too), has access to unlimited hay in pasture from sun up to sun down, and has a few flakes of hay in his stall when he comes in at night. Should I just take him off of oats/grain all together and just have him on hay? He gained weight very fast once he arrived here and seems to be an easy keeper...I don't really know what to do for him. He is my first horse (although I've ridden for 12 years) so I've never had to choose feed for the horses I rode. He is 12 years old and gets worked 4-5 days a week, some days long lining, other days lunging, trot poles ect...were just doing ground work for now...he leaves sweaty and tired but is still anxious once we aren't working. He isn't spooky but is very alert and anticipates everything and makes everything 10x harder for himself.