As RtE says - haylage (spelt like that if you're googling) is same as hay but wrapped much sooner so it partially ferments in the wrapping. Usually wetter than hay but not always. Very variable quality which is why people often buy Horsehage. Horsehage is an identical product but it is double wrapped to ensure tears don't happen in the wrapping (which will allow the haylage to go off fast) and of a consistently high quality. You can get 3 calorie levels, blue, red and green wrapping. Can't remember which is which but any feed merchants will tell you.