I have horses, so I usually have quite a bit of used or spent hay laying around but do not keep straw? Is it ok to use a little hay in the nesting boxes? Or does it have to be straw? I usually put shavings in the boxes first. I am getting a brand new coop in a few weeks and I wonder what to use on the floor inside the coop? I tried sand in my old (leaky coop) and it was horrible after it got wet. So I am either using shavings or straw in the new coop? Can I use sawdust?