Here, “pasture” is determined by average stocking rate for each area.
In our area, stocking rate is 25 acres per cow/calf unit, or 30 acres per horse.
East of here it drops to less acres per animal, West increases, to where some places not too far West is over 100 acres per animal unit according to each species.
Our horse pastures for just a handful of using ranch horses type is 110 acres one, 120+ the other one, both a mile long each, considering rotation between them and anywhere up to four horses, have carried five in a pinch a couple times for a little bit.
I think that deciding for others how they should manage their horses, what turnout is ideal or acceptable or not for each horse someone else cares for needs to be considered horse by horse, situation by situation.
Our own situation may change some day,.
When it comes to horses or any other in life, it may just depend what fits the current situation, is not all one hill to die on, same requirements for all, as some seem to insist on.
When seven years ago we had this one horse that could not be turned out to pasture, a PPID, cushingoid one, we just made a pen out of a corner of one pasture along the old arena.
He has horses coming and going by him and is fine in there, doesn’t fret, has been doing fine all these years.
Now with just two horses, he gets the run of other pens also.
For this one horse, here, the ongoing management seems to be working just fine, but may not for another horse, with different needs.
In this picture, he is looking intently at a covey of quail bugging it in the distance: