Weight.By weight yes.
By calories... 6.5 grams x 4 calories (for protein)= 26 calories/50 x 100= 52% by caloric content.
So is it weight or energy that our birds are eating to meet? Can we agree on that so we can decide which IS the more relevant matter when it comes to feeding eggs to our birds... at 12% protein, that wouldn't be worth it to me.
@Percheron chick does seem to grasp what I am saying.
Everything in the above books is suggesting that the bird is fed based off of its own age and weight.