I am a definite believer in roughage, roughage, roughage. Unfortunately I don't have any grass on my property, so my guys all get LOADS of hay year round. But with the inconsistencies in hays and soil I don't believe that it is all they need, especially if we are asking them to perform any kind of job.
I feed all mine a handful of feed with the supplement Platinum Performance Equine. It's made to be fed instead of grain, but provides them with everything their bodies need. Even my hard running barrel horses stay looking great with just this supplement and hay.
"Brutality begins where knowledge ends. Ignorance and compulsion appear simultaneously." ~ Charles de Kunffy