Is this the food that you are feeding your Grey ?
http://prettybird.com.ashopcart.com/cat ... |8|&cat=19 If it is, please note that soya oil is high up in the list of ingredients and that right after that the majority of the ingredients are artificial vitamin, minerals, preservatives and other artificial chemical additives. For these reasons I do not like this food and think that this is contributing to your Greys feather issues.
We do know that many birds are or develop allergic reactions to soy and soy products that often manifest as feather problems up to and including feather destructive behaviors. We also know that most birds can not utilize the artificial vitamins and minerals in the same manner as they use the natural ones, and we know that artificial preservatives, colors, and dyes are bad for them. I do not think that there are any studies that give precise information on the symptoms that these ingredients cause due to the wide range of reactions that can and do occur, the majority of the studies just state that bird do not do well with these things in their diet and that some of them may have adverse reactions to some or all of them.
I feed my Grey and actually all of my birds a cooked food consisting of a 50/50 mix of cooked whole grains and mixed vegetables and then add cooked white beans and lentils( for protein) about 20% by volume to the grain/ vegetable mix. I feed this cooked food along with a fresh raw fruit, vegetable and a leafy green for breakfast and for all day long and then a quality seed mix for dinner which is removed when they go to sleep for the night or before they wake in the morning.