Horses will eat anything.
I have cared for a horse that would steal your Cherry Pepsi, drink it all down, then consume a fruit pie, tin and all, with a smile on her face.
She, on more than one occasion, managed to steal hamburgers from people. Ate with gusto.
The old farm vet we had used to say horses were second to only pigs and goats, in that he had never seen a horse eat an entire Christmas ham, only half of one.