Just so everyone is clear...
Daisy Mae is NOT a rat you want to breed UNLESS you know absolutely, positively everything about their genetics(and Jo does, probably 2 generations if I'm correct). High white is not something you want to just play around with, especially when pet stores breed their rats willy nilly to get "pretty" rats that have tons of health problems(visible or carried in their genetics).
If you must breed that rat, for whatever reason, breed them to a safe rat such as a black or agouti self, berkshire, irish, hooded. High White x High White is NOT a safe breeding and will usually result in megacolon babies as well as offspring that carry the gene. Something that we, as professional pet rat breeders, have tried for YEARS to get out of our lines. It is not something to mess with.
A friend of mine recently rescued a black husky top ear female from a pet store in Ft Worth. This rat had 7 babies on her, as well as being pregnant(not the way to get things done if you want to KEEP your breeders longer than 3 months..). There was a black wedge-blazed husky female in the first litter as well as a husky female that both ended up with megacolon, one not as severe as the other. They were both humanely euthanized as it is not a way for a rat to die(slowly starving to death and becoming impacted/bloated). The adult female was obviously bred to another high white male ONLY to make "pretty" babies... And this resulted in babies dying, and the other babies being carriers. Just be careful and KNOW your rats' genetics before placing them together.
Megacolon also happens in lethal white paint horses, which is why you never breed homozygous x homozygous.





