I heard straw does not mold like hay does. I have been adding to my flooring too. So far I have used pine shavings, straw and dried maple leaves as I have 5 large maple trees on my property so they are plentiful this time of year. My silkies do not roost they huddle on the ground at night, so I have added an insulated igloo dog house and training them to use it.is straw better than hay? I have mostly hay, but can get some straw if it holds the heat better.