Thanks for your feedback Wolfy-hound. I did some more reading and several sources say that they need more fat / protein because it takes more energy for them to keep warm.. Which makes sense. I use an 18% protein diet for all my rats, so I think that should be enough.

Have you had any eye issues with yours? Some of the sources I found say that they can have eye problems due to lack of eye lashes and getting debris in their eyes.