no, feeding chickens or any animal for that matter mould is a bad idea. its not good for them and can make them very sick. in some animals like sheep and cattle it can make them abort their babies, so I would assume it would affect the eggs, which would not be good for hatching /eating. they will have sweated and then gone mouldy from this ( its a catch 22, you have to keep them dry but let them breathe) since they are going to be in the garage I would suggest an air tight container with a few air holes drilled in them, if the holes are big enough for mice etc to get in then put some hard wire mesh on them. a wheelie bin is a great way to keep feed, I keep all my adult chook food in one here, it has holes drilled in the lid ( it came like that) and its been great because nothing can get in and the food can breathe.