The ground has been in CRP for 20 years, before it was used for hay.


With this I would assume he is not looking at a New Zealand lush 12 month grazing.
Most people do not put their best most productive ground into CRP. Plus we do not really know where he is, what is his climate and what soils does he have to work with.

It has been my experience that the typical recreational livestock owners get their animals before they even look at the grazing potential. They may look lush and green from the road, but are bitter weeds standing a foot tall with little forage.

To top it off he mentions growing hay on a 5 acre patch, a patch that has been grazed.  Possible but doubtful.

Now IF his THERE is in parts of Georgia, Alabama, Mississippi, or Louisianan where the rainfall is plentiful and dependable, and IF the friend was ready to provide some intensive management 5 maybe 7 horses might work.
I emphasize intensive management.
Fellow who was with the Texas Extension Service fed a couple of horses on one or two spare town lots.
Forages were his speciality.
Dale still had to purchase a fair amount of hay to make his system work.
Also fed lawn clippings to stretch the grazing.
Most important was Dale did not allow those animals on the "pasture" unless there was enough grass.


Turn into a 5 acre patch 3 to 5 horses and a year later the ground will be packed tight enough to support a highway.

Really they should visit their local Agricultural Extension Agent and or their National Resources and Conservation Service for the forages best adapted to their climate, and soil.

Unfortunately he/they will probably be purchasing enough hay to feed hay 12 months and not have enough hay storage for more than a months worth of hay.

For what it is worth I do have one neighbor who has a cow calf enterprise, and even with record drought has not fed any hay this year. He owns half the number of mama cows that is thought prudent for the area.
We have  cattle owners who have HAD to feed hay for 6 months now.
When it does rain it will require years for their grass to recover, with management.