Let's say you go out to feed some hay to our horse(s). You have spent the big bucks to buy quality square bales. You pull a bale from the bottom or outside of the stack and notice a bit of mould on one side where some moisture has got in the bale. You open the bale and see the mould has penetrated about 2" on one side only. What do you do? Do you...
Throw out the entire bale. After all it is contaminated.
Separate out the moldy bits and feed the section that looks good.
Shake the mould out of the bale, water it down and feed it.
Just feed it and let the horses pick the good stuff.