I would have to say that I have no scientific evidence to back up what im about to say but my rat snake I use to have went #2 a lot more often then my ball so im thinking that rats and corns are from the swampy South so there's probably more food running around for them to eat than the balls have access to in africa.

The rats don't need to use as much energy completely digesting their food because there's plenty but the balls might go a while between so they stretch it by digesting as much as they can? Lol