If you go to the trouble of crumbling any healthy rabbits pebbles up in your fingers you will find fur loosly holding them together.
Rabbits have no mechanism to be sick so what goes in one end , comes out the other.
Now then if your rabbit is on the correct high, high, high fibre diet all the fur gets pushed and taken through by very large quantities of fibre and as a rule no problems are encountered and this is normal.
I know pineapple amongst other things has an enzyme in it that can sometines help in gut stasis problems but as far as I am aware this does not help in the breakdown of the fur.I stand to be corrected if I am wrong.
Any doubt as to wether your rabbit is normal fit and healthy with good teeth and on the right diet and you should seek good veterinary advice before you change his diet in any way.
hope this helps
alan