Mine had access to full hayfeeders from Nov onwards, they didnt touch it until the grass quality dropped off and ground went wet at xmas... They picked at it, and now they're eating a Quad a week for 60 being fed at the mo. Their is about 3 inches grass left - they did reject some small bale stuff tho, so it could just be an off bale, not to the taste they like.
Oddly they clean out the horses straw bedding if they can get to the field shelter.....