A.T. Hagin writes on another thread:
... At the end of their second year the older birds would be culled unless the farmer was doing his own breeding. Then the best of the older birds would be retained for that purpose...
There are different ways to answer this, but the farmer in this case was not looking for peak reproductive years. He was choosing his best stock to reproduce so he could maintain or maybe improve his flock.
The "peak" productive years are usually pretty young. Those young roosters can a pain but they will keep a lot of hen's fertile once they are old enough for the hens to accept them. First year pullets and hens will lay a lot of eggs compared to later years, so you could consider those "peak" productive years. But you don't get to see their productivity to decide which ones you actually want to breed.
Thank you. So a rooster's reproductive peak is in his first year or two and possibly a hen's her first year? I realize that they would be older to judge type. I also read somewhere to evaluate progeny before any culling also. Is this still a common practice for some?