Hi Jordan
Which feathers are turning dull and grey?
A feather is what it is when it is formed and unsheathed.
So if its a white fluffy under down feather its already whiteish grey in colouration.
If your talking about the outer feathers that are green and are saying they are changing colour then they only change colour when they get dirty or damaged say like rubbing against things like toys which removes the pigmentation of the feather turning it black which is called feather bronzing. Somewhere on this site I uploaded a load of photos and a document regarding feathers that shows the different types of feathers and their damages alterations etc sorry a bit pushed for time have an appointment to go to shortly so will have to find it later unless somebody else can find it!
If the feather is an outer feather and it is turning white then its bleaching and that is usually caused by contact with something that is removing the pigmentation of the feather. Would have to see a feather to tell you better as to what your seeing.
But a feather is what it is when its fully formed it isn't altered by the birds diet or body after its formed.
Do you have an avian light up for your bird?
Remember also the first set of adult feathers that a youngster gets after fledging will be trashed basically as babies start getting into all sorts of mischief and naughtiness landing wrong playing like mad things possessed people often thing OMG but its part of the learning system and the first proper moult will sort it out. Your first moult for you baby should be late December early spring time and won't be a full heavy moult it will be a gradual replacement. Damaged feathers that come out now will just be replaced as needed.
Sorry got to dash running late!
@Jordan