Changing to rats depends on the snake. My 3 y.o. ate live mice all his life till i got him 2 months ago and he switched to frozen thawed rats immediately. I havnt tried rats yet with my babies but id like to get them up to at least 200g before i do. I believe there similar to a person eating. Not everyone likes the same things and getting a baby to eat it, is far more challenging than an adult.