I would like to highly recommend on an EXCELLENT dewormer the FLUBENOL 5%
(Google "FLUBENOL FOR POULTRY ") IT HAVE A VERY BROAD SPECTRUM ACTIVITY AND THE BONUS IS :NO withdrawal time in laying hen!!
Here I can get it for 300 shekls = 85$ for 600 grams and it is sufficient for 1 ton of feed...
All they really need is a hot spot that they can converge under when cold, a lot of free and cool space when hot, clean water, food and the very important ventilation.