hey how r u
well it does vary alot we farm them commercial now from small acorns might oaks grow as its happened
we are just putting in some new p.o.l birds at the end of next month we order the birds as day old chciks then they are reared for us up to 16 weeks old , on our old contract we had to get rid of hem at 72 weeks of age but they will still lay , they will lay up to three years on some occasions ,however the shell quality will go down a lot and the number of eggs will decrease,
some breeds will just stop after a couple years others will push on for another but over the years the crucial thing we have noticed if you bring the birds into lay to early not allowing them to put on enough weight then it will reduce there laying life
allowing them to molt over winter will refresh and keep them laying for longer the longest we have kept a flock in lay was 108 weeks but the % of lay wasn't very good towards the end and the number of poor shell eggs even with oyster shell and grit plus extra water based vits made little to no difference hope thats answers your question