Enjoying watching my young girls grow

[StinkyAcres]

They are 7 weeks old. I've been feeding them Nature's Best Organic Chick Starter Crumble. Their analysis states not less than 20% protein. They are growing quite a bit. They were 5 weeks old when they came to me and have more than doubled in size in the last couple weeks.

That sounds like a good feed. Something does seem to be bothering their skin or feathers. The bald spots around their shoulders and rear ends and missing tails are odd. Have you noticed any lice or mites?