Healthy hens can live 12 years or more, although they typically pass their prime by the age of 3 to 4 years. In the days when chickens were kept primarily for eggs and meat, hens were rarely kept past their prime years. Today, when many chickens become beloved backyard pets, their keepers are often unprepared for the transformations that occur as a hen ages. Here are six changes to watch for in hens that live to a ripe old age.
1. Appearance & Activity
As a hen ages, her legs and feet get thicker and rougher. Some hens—most notably old-style large Old English games—grow spurs. The older the hen gets, the longer the spurs are.
Older hens develop rigid breastbones, compared to the more flexible breastbone of pullets. Seniors also have firmer muscles and thicker, tougher skin, compared to the soft muscles and papery thin, somewhat translucent skin of a pullet.
Older hens generally feel more heavy and solid, unless they develop one of the conditions that cause an aging hen to lose weight. As a hen ages, she will tend to be less active, moving less spryly than she once did, and she will often walk a little stiffly. In a flock that includes young hens, older hens gradually lose rank in the pecking order.
2. Fewer Eggs
The older a hen is, the fewer eggs she lays and the less regularly she lays them. For a healthy hen, egg production drops approximately 10 percent each year, compared to her first-year production rate.
For example, a hen that lays 180 eggs in her first year can be expected to lay:
- Approximately 160 eggs in her second year
- 110 eggs a year at the age of 4
- 55 eggs a year at the age of 8
- 35 eggs at the age of 10
A healthy hen that lives to the age of 10 or 12 years should continue to lay at least a few eggs. A hen that stops laying altogether has some condition that interferes with laying—often the condition is obesity. (See “Signs of Obesity”sidebar below.)
3. Bigger Eggs
Although an older hen lays fewer eggs, the eggs are larger, the shells are thinner, and the albumen is runnier. If the hen lays eggs with brown shells, the shells will be a paler shade of brown. The usual explanation is that as a hen’s eggs get larger, the same amount of brown pigment has to cover a larger surface area.
This explanation, however, doesn’t account for why the pointy end of the egg tends to be lighter in color than the rounded end.
4. Excessive Fat
As a backyard hen ages, she can tend toward obesity, especially if fed an improper diet or too many treats.
Chickens evolved with the ability to develop an abdominal fat pad to use as reserve energy during times when forage is scarce. Most young chickens, especially active free-range birds, have a relatively thin fat pad. In general, an older chicken has a thicker fat pad than a younger chicken.
Old hens, especially inactive hens fed too much grain, can accumulate enormous quantities of fat, to the point that the abdominal cavity is virtually filled with fat.
Heavy breed hens that are characterized as being cold hardy conserve fat more readily than lighter Mediterranean breeds, and therefore more easily become obese. Besides interfering with laying, obesity can lead to significant health issues.
5. Sex Change
Spontaneous sex change is a phenomenon whereby a hen develops the characteristics of a cock. A hen has two ovaries, but only the left one produces eggs, while the right one remains undeveloped.
If the left ovary becomes inactive, testicular tissue of the right ovary is stimulated into functional activity. This results in the hen getting a dose of the male hormone responsible for crowing, enlargement of the comb and the development of male plumage.
Sometimes an aging hen will crow during nonlaying periods, when male hormones exert greater influence than female hormones. Sex change in an older hen indicates she is reaching the end of her productive life. Spontaneous sex change can occur earlier in a hen’s life if the flock lacks a rooster or the hen has an infection, tumor or other disease.
6. Deferred Broodiness
Some breeds rarely become broody when they’re young but may brood as they age. This deferred broodiness trait is especially typical of Chanteclers and Fayoumis. Individual hens of other breeds may experience deferred broodiness, as may hens resulting from a cross between a hen of a breed that typically broods and a cock of a breed known for lack of broodiness.
Even though a hen’s egg production declines over time, if she has a history of successfully brooding chicks (whether deferred or not), she will still make a good mama hen despite her age.
Sidebar: Signs of Obesity
A hen may be accumulating an unhealthy amount of fat if:
- She lays too few eggs for her age.
- Her eggs have poor shell quality.
- She frequently lays multiple-yolk eggs.
- She lays eggs at night.
- She prolapses—pink tissue protrudes from her vent after she passes an egg.
This story originally appeared in the November/December 2019 issue of Chickens magazine.