I used to have some chickens, but I moved and had to give them to my friend. I'm in a position now to have chickens again, and she still has some of my old birds. I want some like them, but she's not set up to hatch out a clutch. She said I could borrow a roo and hen to "make" my own. It's a mixed flock, so it's not guaranteed that she's not going to lay mixed eggs when I want pure eggs. My question is how long do I have to wait for her to get any other roo's "contribution" out of her system?