*from rabbitgeek notes 11-09-07*
The only time I would use salt licks is if I was not using pellet feed. Home made rations would require additional minerals and salts. The feed list recommended by House Rabbit Society is also very weak on minerals.
I don't use salt licks or salt spools. My pellet feed contains all the sodium and minerals the rabbits will need. Another reason for not using salt licks is that if you hang them on the side of a wire cage, the salt will corrode and rust the wire.
If you decide to use salt licks, hang them from the ceiling of the cage like a hanging toy so it does not touch the sides of the cage. Hang it at a level that the rabbit can reach up to lick the salt
spool. Now it will not corrode the side of the cage and the rabbit has a play toy!
Have a good day!