Eeccchhh!!! Doesn't look like freezer burn to me, I can't see any ice crystals. Might be some type of fungal or bacterial growth? I wouldn't feed them. Better to be safe than sorry. I would contact whoever you got those from, show them the pics, and ask for an explaination.
Freezer burn looks different on rodents than it does on vegetables.
It's definitely freezer burn.
I don't suggest feeding it. ;]