I have quite a lot of NN X Brahma (mainly X Blue Partridge Brahma) and they are BIG and heavier than a standard NN. I am wondering, ReiMiraa, what size your Brahmas were? British Brahmas rend to be on the big side (a recent rooster I lost was over 14 lbs). My alpha hen weighs over 10 lbs. My Blue Partridge Brahma boy is a lightweight, but is tall.
I have the male equivalent of your blue female (as well as 3 like her) ....yes, that's Gordon.....and he is not so heavy but he is VERY tall....several inches taller than his father, and runs like a sprinter on steroids.
I don't give any of my birds different treatment unless they are ill, but they are all spoiled and have 40 acres to free range should they want.(Only my La Flèche take much advantage of this!)
These NN X Brahma crosses have come into lay at about 6 months and are VERY reliable good layers of large light brown eggs.
Their cold tolerance (and wet tolerance) seems excellent....as do my pure bred NNs, and they have feather reduction, but aren't nearly as lightly feathered as the pure NN. Their legs are very lightly feathered (in contrast with my Brahmas who have very thick and heavy leg feathering).
They males look rather 'gamey' and don't carry a lot of meat, but seem to be very fit and muscular.
Anybody else have opinions on this?