I’m relatively new to python keeping but from what I understand it’s more sustainable in the long run to start on rats as opposed to mice mostly because it’s hard to switch to rats later on because the smell is different and also because all a full grown blood will ever need even as an adult is a jumbo rat, I’ve gathered That a lot of people because of their size think they need rabbits or something as adults and I guess the general consensus is that it’s frowned upon to feed larger animals to them because their prone to obesity and their metabolism is very slow. But from what I have gathered from my own blood is that switching them to anything shouldn’t be to hard LOL he would probably try to take a horse if it could fit in his enclosure lol