Yep, I know. When I was breeding mice, I sealed the bag first...learned that lesson.

What I meant, was that it's really helpful having a vacuum sealer to REseal the bags. I get my rodents in sealed bags as well. I take them out of those bags and place them into bags for my sealer with long ends for multiple resealings. The rodents last longer and stay 'fresher' that way. It also helps that I got a chest freezer recently.