As for long term sustainable flock: IMO, if you always hatch the best eggs from your best layers, over time, you are going to be improving your flock. Choose eggs that are well shaped, from hens who have good size, body conformity, are frequent layers, and produce a large egg. She should also have a mild temperament, and show good disease resistance. Want to breed broodiness into your flock? Hatch eggs from your broody hens. As for your rooster: Choose a boy with good temperament, good body conformity. If he's second generation, his mother should have all of the previously mentioned characteristics. If these criteria are met, the flock should improve in quality instead of declining as suggested by Mrs. K. Every now and then, a new roo will need to be brought in to prevent issues from continued inbreeding. However if the initial flock is made up of a number of different breeds, that should not be required any time soon.
