I really believe there are lots of different ways that keep our minis in good health and each of us tends to find the one that works for us.
I know that many beautiful show horses are fed lots of protein and concentrates and look great!
I do not show much at all, and do not keep my horses in show shape, but they are in good flesh and healthy. And I know that for me, I am fortunate to have some of the very best grass hay around, with protein levels not as high as alfalfa but higher than most grass hay. It is largely timothy and grown at our altitude of 7500 feet and it is by far the main thing my horses eat.
I know they like to be munching or grazing probably somewhere between 50% to 80% of the time. I do think that is one trait that is universal to ALL horses.
I also feed Super Horse Manna Senior feed since it is easily digestible and they each get around a cup of that a day with Horse Guard added since I found out our good hay, is low in selenium.
In the winter here they pretty much get hay free choice as I know it wll keep them warm and not run the risk of colic or founder like feeding richer feeds.... free choice.
But our winters can be fierce, and my horses live outside with run in shelters and tend to be very healthy and hardy.
Also my little 24 year old stallion gets himself very thin in the breeding season, and more so now that he is getting older. I kept increasing his senior feed last year until he was getting around 7 cups morning and 7 at night with about a half cup of BOSS daily also, and he put his weight on his topline nicely with that much, and was in great shape for the winter.
At any rate, I do hope you find what works for your little guy (and if selenium helps!) and do agree that many minis can do well on mostly or all good quality hay, since most of mine do.
But I know some need other things as well and am in no way condemning those who feed different ways and whatever works for their minis.
Susan O.