Fine yellow dust / powder in hen house

The floor of my hen house is covered in a fine yellow dust / powder. What is this???

****************************************************
It is dander that comes from your chickens as a result of dead skin cells and feather follicles. Totally normal, and more noticeable during molting time.

However, Marek's disease is spread through the presence of dander, which is a very serious chicken disease, and so therefore it is important that you minimize their contact with the dander by keeping your chicken house as clean as possible.