I use those all of the time when I go deer hunting. I see a couple of problems with using them in the nests. First, they cool off very quickly so they won't retain the heat from the chickens' hineys long enough to make much difference - IF the nesting material between them and the pad even allows for much warming from lack of direct contact. Second, they have a slick side. Your nesting material will slide off and all around. The chickens like to scratch in their nests, getting them all cozy. Whatever nesting material hasn't slid off will be scratched aside, leaving the girls scratching on the surface of the pad. It's only a matter of time until a hole gets punctured, they discover the little beads in there, and eat them. Yep....that could be a problem. I left a veritable trail behind me deer hunting once because a twig on the ground had put a small hole in the pad. The little beads were just dibbling out of it as I walked.
If you do try it, let us know if it works....it would be an interesting solution to a freezing problem.
