its relative to age/size of rat/mouse. an adult mouse (which is equivelent to a large rat pup or so) is probably more nutritious than a newbord rat. but in my opinion, the quicker you can get them on rats, then on rabbits the easier and better. mice are very tasty to most (if not all snakes) which is fine for small snakes that will stay on mice for life. with retics, however, they grow so quick and need to convert so often, it can be difficult to get them (or alot of the larger boids off mice)
-----
retic is king of kings

1.0 Tiger Retic
1.0 Albino Tiger Retic
0.1 Striped Tiger Retic (het albino)
0.1 Salmon Boa
1.0 Albino Boa
0.1 False Water Cobra