Hedge Apples

Our horses love hedge apples (osage orange) and the leaves from the trees. They will eat the leaves and fruit when there is nice green grass at their feet. I try not to let them eat very many, but they love them. Is there any harm besides them having slimmy green slobber lips?
Anyone else have horses that eat them?
For anyone who doesnt know what they look like:

Oh, my boys eat them like candy! Same thing about the leaves when there's grass at their feet.

I think if in moderation, is just fine to eat..haven't had them get sick yet. Hegeapples were a new thing to me, being from Arkansas, and both my horses came from the Ozarks, but they gobble them up and don't have any problems so far. I bet they can overeat them like any food, but haven't seen it happen yet.

I was always told that hedge apples and the trees were poisonous to cattle and horses, but idk, it beats me.