If you cross one breed with another to improve a trait - say, size, or egg production, etc - and then breed the cross chicks back to the original breed for several generations... at what point is it no longer considered a 'cross', but just that breed? 3 generations? 10? Or is it based on the chicken's appearance (if it retained any non-standard traits, like wrong lobe color, or egg color slightly different)? Is it still considered a cross even after 5gen back to the original breed if it happens to keep a trait from the cross (that you weren't breeding for to improve)? Or is it 'xyz breed with x trait'?