I'm wondering what could cause this? Could it be frost damage? Except that it is only in patches? And the grass that is in darker patches is also of a different texture, as though coated in something greasy.
I'm really hoping that someone else will have had this so I can find out whether it's a problem or not. At present the horses all seem to be healthy enough, but they are all generally producing very very loose droppings. I think that's normal though, as they have only just gone out onto the spring grass, and are generally on full grass livery.
Thanks very much! :)