I can't help you with your question, as I have no idea. I just started raising my own feeders and only have two litters at the moment that have yet to get ANY hair, let alone change color, lol! She's a nice looking rat as far as color/patterns go; like the "reduced" look she has.

It could be that her guard hairs are growing out and that she still has the previous pattern under the longer hairs. I don't know though and am just taking a S.W.A.G. (Scientific Wild-A** Guess) at it, lol! Regardless, she's a nice looking animal.