Dry the apple twigs? Why? We have a few apple trees in the backyard, and they need to be pruned to produce well, so I prune them gradually throughout the winter, giving fresh prunings to our two buns almost every day from mid-December through March. (We use no pesticides on our trees.) I've been doing this since the rabbits were less than a year old, with no untoward effects. Wild rabbits certainly eat apple twigs and bark whenever they can get it, too.
On occasion, I give them twigs of other tree species, such as sugar maple, oak, beech, ash, autumn olive, service berry, etc. They like some of these more than others. However, the two that they will not eat are crab apple and black cherry, so I don't bother giving those anymore.
There are many different kinds of crab apple, though, and it's possible that rabbits will eat some but not others. My crab apple trees are Sargent crabs. If you have a different kind, and they do eat it, I would be interested in hearing about it.
Everyone has a different philosophy, but I find out what they like by simply offering it to them. As long as you have not sprayed your trees with chemicals, it is fine to give them some twigs and see if they like it. I always give them fresh, not dried.
