how long to isolate?

[abelseville]

So I just separated a group of welsummers. Storey's guide to raising chickens says 2 weeks before all the old sperm is gone. But from what I read here on the byc some are saying a month! Whats up?

 

[saladin]

A hen can remain fertile for at least 30 days after being with a cock. Question is why the need for isolation? If you put a new cock with them they should carry the new cock's sperm on ar about the 4th egg.
saladin