I have always been a proponent of the "simpler is better" theory. The horses GI tract was designed to thrive on fibrous feedstuffs or forages if you will. (grasses, legumes, hays) Not that concentrates/supplements (complete feeds, grains, top dresses, etc) don't have a place...they most certainly do. The demands we often place on our horses today, coupled with the fact that many horses are grazing on less than the minimum recommended amount of acreage per head and most people not truly knowing the quality (and I mean via analysis) of their hay often makes it a requirement for us to supplement their diet in order to meet their vitamin/mineral, calorie/energy needs. However, any good feeding program should be BASED on forages and MOST (not all) feed products are designed to be fed with an adequate forage diet. Too many people decide what feed to use, then worry about hay and grass later...when in fact its much more beneficial to the horse to reverse that, make sure they are receiving ample amounts of quality grasses and hays, and then do just what feeds were meant to do..SUPPLEMENT the forage diet. There are some quality complete feeds on the market that are designed to take the place of forages...however they don't provide the horse the physiological and psychological satisfaction they receive from grazing, munching on hay. Horses are grazers by nature and need that. Just my .02.