There are charts with nutritional break downs of prey mammals. The debate about value is a bit sketchy as the real question is what exactly are the nutritional needs of a royal python. Believe that rats provide better value marginally but that is a best guess. Rats are more economical and clearly easier. My largest female would need for a 10% meal about ten jumbo mice (50gm) to one jumbo rat (500gm) . (it is debatable if a 5000 gm female should have 10% meals but to illustrate the point...)