i think jimmy is right here i think what i would say is the more experienced fancier would know better how to handle birds better on the darkness and even know how to act in the loft around them causing less stress at the end of the day we are puting birds though a process of moulting by closing up the loft locking out light and this also blocks out fresh air i don't think its the moulting process that the big problem i think its the lack of air in the lofts