I use hay for nesting boxes, and there is some on the floor for litter. I have about a whole bale of hay that got wet. I spent a whole day airing it out in the sun, but it is still a little moldy. I know you're not SUPPOSED to use moldy hay, but what is bad about it? I have so much, that it seems like a waste. What should I do with it if I can't use it?