My worst mistake was a near miss: my other half had a sawmill one winter and frugal me thought “look at all that great FREE bedding!” For a couple weeks it worked, the chooks were delighted because it was soft and warm, and under the heat lamp they would dust bathe and have a party. But I have ducks too. And ducks root thru bedding to nibble up food. After almost two weeks I realized how skinny they were, it hit me that they were stuffing themselves with the sawdust thinking it was food! Did a total coop clean in January and refilled with proper shavings, and fed the duckies grain mash and cooked veg for a week till they plumped up again...lesson learned!