Try melon, pears, rosehips, bananas and two of ours are not adverse to a nip of whiskey not given willingly, we were mugged, my boy loves a drink of tea
If you use fruit, as we do, make sure you give it a good hose out each day or they get really manky and smelly. We pad ours out with chaff or a mix, really whatever we can get through the hole. One of ours has got the trick of pulling it towards him instead of pushing it away, so then none of the others can nick it off him!
Thanks for all the replies, given me lots of ideas. We're feeding him happy hoof so that can definately go in and the badminton high fibre things aswell xx