I just read through one of my BackYardPoultry newsletter/bulletin I get in email- it talked about egg laying. See if you can sign up for it (top right on their home page). I can't email you the link as it's in my email but I'll copy & paste the article:
Decrease in Egg Production Has Many Causes
Q. What would cause a decrease in egg production? Please list all possibilities. What are the ideal conditions for chickens to lay eggs, including light, warmth, etc
-Jerry S. via email
A. I'm not sure I can list all the possibilities, but here are some common ones. Diseases, of course, can cause drops in egg production. This is a common sign of many diseases.
From a management side, I like to look at FLAWS, that is Feed, Lights, Air, Water, and Space. If you mind all of your FLAWS (and don't have flaws!), things will usually be in good shape.
Poor nutrition can certainly be a problem. Feeding a good diet that is nutritionally balanced for layers, with adequate calcium, will go a long way toward high egg production. Excess feed, causing obesity, is not good either. Overly fat hens will have more problems with double-yolked eggs, lower overall production, and other health problems, as well.
Decreasing day length will decrease production, too. Chickens are long-day breeders, so they lay when day lengths are increasing. One common mistake people make when using supplemental lighting is to just put the light on early in the morning. Since the sun goes down a little earlier each day (after June 21), the hen still recognizes a decreasing photoperiod. Lights should really be added in the morning and evening hours if you're going to add them. For optimal egg production, you should have as many hours of light as the longest day in your area. This is not always possible or feasible, but it is probably optimal.
Extreme cold temperatures can cause hens to stop laying. Optimally, temperatures between 50 and 75° F are best for hens' comfort. Likewise, extreme heat is not good. When hens are panting a lot, it can cause very poor shell quality. Air quality is a concern, too, but it usually isn't enough to interfere with egg production. A lack of ventilation, especially in the winter, can increase ammonia and moisture levels. These can increase the chances of respiratory diseases, which would then decrease egg production.
Water is also very important. Feed withdrawal will cease egg production after about a week or two, but 1-2 days of water withdrawal will cause a large decrease. The hens will often molt before coming back into production.
Space is not usually a problem, except that it can cause extra stress on the birds. Excessive stress can certainly decrease production. As an example, I've seen hens that are used to a fairly large pen stop laying completely when they are put in a small cage. This is a reason I suggest setting up breeding pens several weeks before you plan to start saving fertile eggs for incubation. Often, adding new birds to a flock will give a temporary drop in production as the hens are working out a new pecking order.
Age of the hens is also important. Typically, a hen will lay the best in the first two years of her life, then production will taper off after that. Also, egg production for a flock will slowly taper off as the time in lay gets longer. Some hens will go out of production to molt, or just not lay as often, so the flock production will go down.
Breed can also have a large effect. Some breeds may only lay a couple dozen eggs, then decide to go broody, or just stop laying. Others that have been selected for high egg production will continue laying for a much longer time.
-Ron Kean, the Answer Man
