The first year I had chickens (well, second winter - first batch were 18 mos. old), I put lights in the coop, and they laid throughout the winter - then I read about how bad it is for them to not get a break, and I have not since. Those 18 month olds laid much more productively than any other 18 month old. batch I have ever had. So, it is an unscientific study as it was one group (mixed breeds like now - 2 EE, 3 BR, a Partridge Rock, 2 Light Brahmas).
I will say milder winters they lay better...but that is with the caveat that on really cold snaps, they stop or slow down. In moderate cold, my lighter weight girls stop...my heavies keep laying like nothing going on weather wise. I find my 'newbies' lay through the winter if they already started laying. Girls that have molted - depends on age and breed if they atart up again. Older girls, nope, 18 y.o., usually do - but at a slower rate, and again, depends on weather and their body weight. Just like my really heavy girls don't like the heat and during heat waves, stop laying - others might slow a bit, but don't stop in a heat wave.
That has been my experience. Again, unscientific...but I'm pretty confident that light has something to do with it...and also temperature 'stress' impacts lay, just like any stress does.. (i.e. heavy girls in the heat - 'my heat' in the Northeast - and lighter girls in the cold it affects their rate of lay.)
. I still haven't gotten the image of him attacking and hanging onto Russ's tail out of my mind yet!
