Although individual laying hens can live for 10-15 years and occasionally longer, the average number of eggs that hens lay tends to drop off as they age.
We have hens that are productive after 4 years of laying, and we have had hens that died at 2-3 years of age. Things vary quite a bit from one hen to the next.
That’s why, when it comes to egg laying and keeping a productive flock, it makes more sense to think in terms of averages.
A useful rule of thumb is that, on average, your flock will lay about 80% as many eggs with each passing year of laying as they did before.
Let’s look at that in a bit more detail.
Suppose you have 10 hens that started laying when they reached 6 months of age in December of 2019. They layed well for 7-8 months, then went into a molt during hot weather in August 2020 and stopped laying. That time period would mark their first year of laying.
Suppose that you collected a total of 1,700 eggs from them during that time period. That averages to 170 eggs per hen. Now, if you had a way to know how many eggs each hen was laying, you would probably find that some hens produced more eggs than others. Maybe your best hen produced 207 eggs. And your worst 125. But looking at averages, you would say that your flock averaged 170 eggs per hen during her first year of laying.
Then in January of 2021, your hens had finished their molt (at various times — some more quickly than others) and started laying again. This marks the start of their second year of laying. During their second year, I would expect that you’ll get about 80% x 170 = 136 eggs (or round it off, since this is simply a forecast, to 130 eggs) during their second year of laying.
And in their third year of laying 80% x 136 = 109 (or about 110 eggs).
This is about the longest I would want to keep hens for laying unless they had some other purpose. For example, maybe it was an excellent hen, and I wanted to use her for breeding purposes. In that case, I might keep her for several more years.
Again, we were looking mainly at averages. What may actually happen is that one or two hens may die during year 3 from illness or predators. Another thing that can happen is that a hen may totally cease laying at some point and not return to it. Or if she does return to laying, she may so few eggs that it does not justify keeping her.
And you may have an exceptional hen that lays 90% as many eggs in year two as in year one.
Because there is so much variability, and because egg laying declines with each passing year, it’s important to replace at least some of your layers each year if you want to keep your flock productive. I also recommend going through your flock around the time when you start to get fewer eggs from them (for southern climates, this will tend to be as the weather heats up at the start of summer) and remove from your flock hens that are no longer laying. See this article on egg production for more information.