Yea I think a big part of it is the diet. If you feed dog food, be prepared for stinky rats and canabalism. I even had a rat a little bigger than a weaned rat get canabalized when I was feeding dog food. Needless to say I stopped that quickly after. When I was a kid I had pet rats that we fed normal pet rat food from the grocery store and they we're always having healthy babies and I wasn't even trying to breed them. As long as you keep em clean and fed properly, it will be one of the easiest things you've done