http://www.nal.usda.gov/awic/zoo/Who...nal02May29.pdf
This link is to a study of the comparative nutritional value of assorted prey species and includes zoo data as well as combined data from various previous studies. The pages of greatest interest to most readers here are 9-10, 12-14, 16. To summarize the findings, pinky mice may actually be significantly lower in body fat than previously suggested (including by myself on this site numerous times) and are probably a better prey item than previously thought, though adult rats are still the overall winner in the protein to fat and calcium value analysis.
It is interesting to note that the zoo findings regarding calcium content of both mice and rats and protein/fat composition of mice are statistically significant between the previously published data and the zoo data. I would be inclined to believe that prey diet in particular and living conditions to a degree (exercise, stimulation, space) would help explain the difference of almost 2.5% in Ca content of pinky mice, for example, and zoo-analyzed pinkies having double the body fat of the previously studied pinky mice.
Suggestion based on data: raise your own prey items when possible, feeding them according to their purpose. If they will be fed to breeding females, supplement their diet with high-calcium foods, and increase fat content of their diet as breeding season approaches to help sustain the female through egg-laying and fasting.