Straw or Hay gets VERY smelly VERY quickly. I only use pine shavings and it's WONDERFUL. No smells in my coop and I clean it once a year (deep litter method) and I add a new 3 cubic foot bag every three weeks or if they spend a lot of time outdoors I add every month. When spring gets here I shovel the whole works out, clean it well, and put it in the compost pile and start again. I start with two bags then add from there.