Originally Posted by varidgerunner
I have heard from old breeders and used in practice with feather footed versus non feather legged, white ear versus non white ear. After about seven days you would be hard pressed to get anything from the first rooster if actively paired with a vigorous rooster, even if your life depended on it. I am well aware of what the textbooks say, and am well aware of how a sperm duct works. I am convinced that a hen can jettison her sperm duct if she wants to, I know she can't get rid of every cell, but it is a game of odds. 21 days is the textbook answer, but if you are working with something rare that doesn't lay a lot of eggs and you have one start to lay unexpectedly and you throw her in with your choice cock, you might want to start keeping eggs before the 21 days is up. In case you do get a couple off chicks, If you can't tell which ones are the right breeding once they are grown, then it probably didn't really matter which cock they are out of anyway. In actual practice it is preferable to pair them in advance of egg laying.
I agree that you can get away with much shorter intervals. There is variability in the results. A surprising amount of variability. It can vary from bird to bird etc. etc.
It is better to recommend on the side of caution. It is true that a hen can be fertile from a cock for up to 30 days. It is best to recommend accordingly.
I always went the two weeks off and a week on, and never had a problem. I wait a little longer now. I schedule accordingly.
Most of the time, we see eggs candling clear by the third week. And that is the most certain way to determine when it is safe. By candling the eggs.
I would rather be certain than speculate.
It is best to recommend what we know, though there are many variables and exceptions worth discussing.
Our setting and hatching should be intentional. There should be a process that includes a schedule. This schedule should take account of all that is possible.