Have you ever wondered how many eggs a chicken lays and how farmers meet the increasing customer demand?
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It’s well-known that female chickens, also known as hens, lay eggs. But, have you ever wondered how many eggs they lay and why? Or, have you ever considered who chickens are beyond their ability to produce eggs? That chickens lay eggs may seem simple and natural, but today this fact - and how many eggs a chicken lays - has become greatly complicated due to the rise of factory farming.
There are two types of chickens on factory farms: broiler chickens and layer chickens. Both have been bred over generations to be especially efficient for either meat (broilers) or eggs (layers). Male chicks born into the egg industry are separated from the females. Because male chicks can’t lay eggs, the vast majority are immediately killed, often via gassing or maceration. Meanwhile, broiler hens are typically killed for their meat even before egg laying age, with only the exception of those kept for further breeding.
How long does it take a chicken to produce an egg?
It takes a little more than one full day, about 25 hours, for a chicken to produce an egg. First, the chicken’s ovary creates and releases a yolk. As the yolk moves through the oviduct, the egg white then gets added over a period of about three hours.
Next up is the shell membrane, which is the thin tissue paper-like layer just under the shell. The shell membrane is responsible for holding everything in place while the shell forms on top. The shell takes the longest to form - 19 hours - in the hen’s uterus. This is also where the pigment will be added for blue or brown eggs.
At the very end, right before the egg is laid, the bloom is added. The bloom is a thin protective layer that prevents bacteria from getting in.
In Europe, eggs are not washed before hitting grocery store shelves, so the bloom stays intact. Overseas in the United States, all eggs sold commercially have to be washed, a process that destroys the bloom. This is why eggs in North America are typically sold refrigerated.
How many eggs do chickens lay?
The closest living wild relative to domesticated chickens is the red junglefowl, who lays between 10-15 eggs per year. Outside of egg farms, chickens lay eggs for about eight years. Factory farmed chickens, though, lay far more due in large part to intensive breeding and the manipulation of their environment (more on that below). As a result, factory farmed chickens lay about 25 eggs per month, up to about 300 per year. After a year and a half or so, that number then naturally starts to fall. This is why on egg farms chickens are ‘culled’ - or sent to slaughter - at about 18 months old.
Why do chickens lay eggs every day?
Chickens typically only lay eggs daily during the warmer parts of the year with longer days. On farms though, lighting is manipulated to be consistent throughout the year. This makes chickens lay eggs daily without pause.
Which chicken breeds lay the most eggs?
There are several breeds that are bred specifically to maximise the number of eggs they lay. Unfortunately, increased egg production often leads to decreased welfare due to the toll laying more eggs takes on a hen’s body. For example, laying a greater number of eggs can lead to calcium deficiencies, which in turn can lead to bone breaks and fractures.
Some types of chickens bred to lay a maximum number of eggs include Lohmanns, Bovans, and Hylines.
How do environmental conditions influence egg-laying?
The environment a chicken is kept in has a profound impact on their health, wellbeing, and the number of eggs they lay. One of the most significant influencing factors is light. How many hours of light, the light’s colour, and even how bright it is all play a role in how many eggs a chicken lays. Chickens see a broader spectrum of colours and light than humans do. The type, colour, location, and brightness of light all work together to determine how well a chicken can see and interact with the world around them.
Chickens are biologically geared to lay eggs during the times of year that have longer daylight hours, so producers will manipulate light, keeping lights on for up to 16 hours a day in order to trick chickens into constantly laying a maximum number of eggs year-round.
What are chickens fed?
Chickens kept in backyards are typically fed grain mixes specifically created for chickens that can include a varied mix of corn or wheat, added nutrients, and sometimes omega-3.
On factory farms, however, the key ingredient in chicken feed tends to be calcium. This is to support shell formation and healthy bones, though there is often still not enough calcium to prevent bone fractures or breaks, due to the strain that high production puts on the birds’ bodies.
Despite the popularity of eggs that come from hens fed a vegetarian or vegan diet, chickens are actually omnivores and rely on other sources of protein in order to be healthy.
How much space do chickens have?
Instead of providing chickens with the wide-open rolling fields often featured in egg industry marketing, many egg-laying chickens are locked into cages with barely enough space to stand or fully extend their wings comfortably.
While traditional battery cages are banned in the EU and UK, egg producers have instead moved to what are called enriched cages, which continue to confine chickens and cause much suffering.
Is laying eggs painful?
Egg laying does not appear to be painful in and of itself. But hens on factory farms are bred to be physically small and to produce large eggs, putting strain on their bodies as they lay, and putting them at risk for painful keel bone fractures. According to the Welfare Footprint Project, keel bone fractures are "the greatest source of physical pain that laying hens endure during their lives". So although egg laying may not be painful, the conditions in commercial systems can lead to significant and painful injuries.
How you can help chickens
One of the best ways to help chickens is to simply stop eating their eggs, especially the ones you can grab conveniently at the grocery store. Instead, opt for egg replacements like aquafaba or plant-based egg products, or seek out a friend who keeps them in their backyard as beloved companion animals who offer extra eggs.
You can also join us as we fight to eliminate the worst suffering for layer chickens on factory farms.