There are several ways to improve your chicken tractor. First, make a perch in the run area so that the chickens can hop up off the ground. This can provide entertainment which may keep them from pecking each other. Secondly, allow for a portion of the run to be in direct sunlight to give the chickens a chance to sunbathe.  Often they will scratch dust into their feathers as well. This is one way that they keep their feathers and skin clean. If your chicken run is in the sun, make sure they have shade as well. This can be done by spreading a blanket over top of the run. Thirdly, move your chicken tractor more often. This gives your chickens more access to bugs and fresh grass, both of which are good for health and eggs.