For years i used to start hatchlings off on mice pinks cause i was always told they have more calcium but for the past 5 years i feed rat pinks to my hatchlings for their first meals and keep em on rats their entire lives. Ive got some huge female balls and im talking gigantic. Ive got 6 girls that are over 4000 grams that have been on rats their whole life and now they eat jumbos. I do however have to take precautions when feeding them cause a rat bite sucks and you can imagine the bite a jumbo can deliver to a ball so i knock em out and yank the teeth. Now i also have 3 girls that i bought a year ago that were fed mice only and they are the same age as my big girls and they only weigh in the 1500 gram range so i dont know if that helps but over the years ive found they put on the weight and hold it better on rats