This is our situation right now:
Living: On pasture all day, with both grass and round bales available. Muzzled half of the day (in spring he was muzzled half day and slowly dropped some weight. Summer when everything got brown I left it off, but he still put the weight back on. Now he's back in the muzzle).
Feed: Twice/day he's brought in and given half a scoop of grain. It's something the neighbor makes, so I don't know the exact ingredients, but I know there is absolutely no molasses or sugar in it - I verified that.
(As a note, after everyone comes in and is organized with their half-scoop, the barn manager goes down and gives extra to whichever horses need it - so it's individualized, but everyone still gets at least that half. That way he doesn't have to worry about making sure they go to their correct spots - he just feeds the extra based on wherever they ended up).
Exercise: Normally he's worked 5-7 days/week for 1-2 hours/day. Most of that is on the trails, walk/trot (occasional canter), but up and down lots of hills.
Condition: Somewhat overweight, but some decent hind-end muscling from all the hill work. Not a horrible weight at the moment, but it only takes air to put it on him.
He's a Morgan/Paso Fino cross, about 14.3h.
Once he moves to the stall, the only thing that will really change is feed. The living situation will still be on pasture most of the time (muzzled half-day), coming in to eat or for bad weather. But since they're assigned stalls, I don't have to give him that minimum half-scoop of grain anymore.
Should I keep him on some grain? Use a different grain? Supplement?
I'm thinking maybe a handful of grain with a multi-vitamin (Accel)? Any thoughts on that?
As a side note, I have no idea why these guys are called "easy keepers" - keeping weight OFF him is about as difficult as keeping weight ON my old mare I used to have. Nothing easy about it at all.