If possible try and raise your poultry house a couple of feet off the ground and have it so as there is an open space unerneath the hut visible from all sides.
This will discourage the rats from burrowing under the hut as it makes them vunerable to attack.
Second thing, rat poison, there is always the possibility of children, cats, dogs picking up the poison, try putting it into a lockable box.
Something like this -
Generally these boxes have rods in that you scewer the poison onto. USE DISPOSABLE GLOVES WHEN YOU DO IT AND DON'T ALLOW THE POISON OR OUTERSURFACE OF GLOVES CONTACT WITH YOUR SKIN.
Also about once a year change the poison product
