I don't know about pigs but grass mowings are dangerous to horses and should not be fed (except maybe a tiny tiny amount and then only if extremely fresh - imo better not to anyway). as well as possible contamination from oil or petrol if the grass is cut by a machine, lawn is often fertilised and quite rich. However, the main problem is that lawn mowings get very hot when heaped together - put your hand in a pile of clippings and see what I mean. Very bad for horses but can't comment for pigs. Great animals Kunes aren't they - we used to have a couple where I lived, very tame, highly intelligent and I taught them to sit and hold out a trotter for a food reward!