Great Oregon Extension Services article. Thanks! We acquired our chicks at Easter in 2009 and they produced their first eggs in about June of that year. We didn't know any different, and apparently neither did they, because they produced well into the fall. 10 hens, about 9 eggs per day from the lot! Lots' of double yolks in mega-eggs as well. One prolapsed cloaca, which I persisted in pushing back in, smothered in both antibiotic cream and Prep. H, as per my local vet. He said the birds almost always succumbed, but I didn't give up, and two weeks later it was A-OK and she was a prolific layer right up until one of my rural neighbour's dogs ran up and killed her right in front of me. Sorry day. Shoulda shot that darn free-ranging dog.....
Anyhow, this past fall, as of about Oct. 15th, they all simultaneously stopped laying for all intents and purposes, over about 2 weeks. This accompanied their recovery from both natural molt and their own internal bickering (they were in too small a run area; 8 birds [one died from disease] in about80 sq. ft. Now it's better: about 120 sq ft for 8 birds. The result was a lot of big patches of bare skin. All healed over now!)
As of this past two weeks, despite bitter cold and wind (-8˚ F some nights) they are now coming back on-line. I didn't like the article's mention that they will really slow down at about 18 mo, and then stop at about 3 years, since I'm there @ 18 months now, but my local egg-raising friend says that's just not so. She has chickens well over 4 years old that produce about 3 - 4 eggs per week.
Question: the hen that the dog killed became a slightly tough slow-cooked chicken stew dinner. (BTW, that ended the controversy about whether you could eat a pet hen you'd named. Didn't seem logical to just toss her...) I took the opportunity to do a bit of an internal physiological examination (I am a wildlife biologist after all...) and noted with great interest the oviduct layout inside Piccolo. The starting point is a cluster of already-formed tiny egg yolk sacs, a cluster of, I estimated, about 120 of them ranging in size from <1mm to about 6-8mm.
The connecting duct had 3 yolks in it, ranging in size from about 1cm (10mm) up to about 18 - 20mm (just under one inch). I wondered if they have a set number of egg yolks, as in human females, and when they're gone, that's it. I'll assume there's a few other very tiny little proto-egg yolk sacs developing under the cluster of visible ones, yes? Anyone know the answer to that?
We're back up to about 3-4 eggs per day now. They have access to a thermostatically controlled [32˚ to 40˚ temp range via a Thermocube controlled outlet] and well-insulated coop, so they are not stressed too much by this cold weather. They also get some morning and noon-day sun, even despite the cold temps.
They, and I, am now officially looking forward to about April 1, 2011 and a return to more rational temps!