ok, just wondering if anyone has a big feather eater?

i dont mean just the pretty little fluffy ones, or gettin stuck in/on her beak, but she will actually bite off, and eat the bigger feathers too...

i understand this may happen in the wild.. but it can happen a lot sometimes.
should i be using the shell grit i got? coz ive been told they dont need it and i havent seen it mentioned here, maybe its a digestive kinda thing? i have so many ideas, no solutions, google hasnt given me much