I emailed them asking them what the ingredient was. I will share here if they respond. I am just so paranoid with my recent run in. Lots 4 pullets to it and 2 of them were my French Black Copper Marans pullets- the only 2 I had.When I googled A. Niger all that really came up was mold. Aspergillus Niger. It says A. Niger fermentation. I am curious about this ingredient though. Wikipedia lists some others things A. Niger might be http://en.wikipedia.org/wiki/A._niger The label doesn't state what the A. Niger is exactly. I am going to look into this further. Once I put my mind at ease- this looks like a really cool thing!