Re: mice vs rats .. question
"IF" you can get a mouse eater to eat as much weight as a rat eater each month then you'll see a similar weight gain.
Most mice eaters can't/won't eat as much weight per month as rat eaters.
Re: mice vs rats .. question
I agree with Mr Kewl :) And, it will be so much easier to feed an adult bp rats. Since, i'm pretty sure no mouse in the world is going to weigh the same as a small rat. like a 70 gram'r. Unless of course you have access to some jumbo mice. Also, make sure it is a big healthy mouse. A fat mouse, will not provide as much nutrition as a healthy rat the same weight. It's easier to switch a young bp than an older one from mice to rats.
Also, when he reaches a certian weight his mice quantity will increase. It's more cost efficient, for me, to buy a 70 gram rat than 2 big mice (or 3 smaller ones).
Re: mice vs rats .. question
Gram per gram is all the same the only difference is that sooner or later you will have to feed multiple mice instead of one rat if you keep feeding mice, and obviously it's something to consider price wise and time wise.
The bottom line is to feed what work and what is convenient.