Hi, I am not an expert, but have been grazing 2-3 horses on pasture and some widely spaced
trees (in KY) for 8 years.
my guess is there is nothing for them to eat in pine woods so you will be into a lot of
hay ($).
Like the grazing information on this site emphasizes, you have to split your land up and rotate or you will end up with a weed patch.
The first year they had the whole pasture which was mostly fescue and some clover, they ate what they liked down to the
roots and destroyed it. Pooped on what they didn't like so that grew great. (lawns and roughs)
We split it into 3 pastures and rotated and it was some better.
We added a sacrifice area (coral/round pen) to keep them in and
feed hay when muddy or drought, it some what recovered.
This winter they had a run so they are off the main pastures all winter(horses are athletes and need exercise). we added sheep we will graze after the horses go through to eat weeds and distribute fertility.
We will also split the main pastures up with poly rope and step in posts to graze in smaller areas for less time.
I have high hopes for this grazing season and will keep tweaking till we get it right!
If you feed roll bales the horses will waist a lot of it and trample it into mud which makes a good garden spot.
also make sure there are no places (corners) they can trap each other in because the weaker one will get hurt.
Horses are a major pain in the behind but I love them. Good Luck!
University of Virginia has some good info