Virginia,
I'm not so sure it's a matter of hay versus pasture. Too much of a good
thing (in either case) can make a horse gain weight.
How about grazing muzzle(s) for Gat and / or Orri to be worn for part of
their turn-out time? I like the kind that are for both cribbing and to
limit grazing. Those have a metal grid at the bottom with a removable
rubber
circle that fits over the grid. The rubber circle has a hole in the center
about the size of a golfball.
With Soley, I take the rubber circle out and leave her with just the
metal grid on. This lets her get a fair amount of grass, but seems to slow
her down quite a bit.
Rocky wears the full set up with the rubber circle in place and only gets
the odd blade of grass here and there.
The muzzles let them still have access to a larger area to wander, gives
them nibbles here and there, but doesn't let them eat as much.
It might be just the "portion control" Gat needs.
Soley (also 19 like Gat) slimmed down enough that I have actually been
turning her out without the muzzle for a week or so now. However, if her
waistline starts to creep back up, on it will go again. Now, I am thinking
Eitill needs to wear it for awhile. . . .
-- Renee M. in Michigan