Everything You Should Know About Battery Cages

The welfare concerns arising from barren battery cages are what have spurred many countries and states to phase out or ban these cages. But first, it’s important to understand exactly what a barren battery cage is and why it is so harmful to laying hens.

What is a barren battery cage?

A barren battery cage, sometimes called a battery cage or conventional cage, is a housing system for laying hens—female chickens who produce eggs. After hatching in hatcheries, the female chicks may undergo the process of beak trimming (also known as debeaking), and will go to the laying hen farm at around 16-18 weeks old, just before they begin egg laying.

While designs may differ based on country or individual farm, barren battery cages are generally made of wire on all sides, including the bottom, so that waste falls through to collection troughs below. The floors of battery cages are sloped so that eggs roll down toward the troughs on one end of the cage, where the eggs are then carried away via conveyor belt. A feeding trough is located on the other side of the cage, and while food is generally always available to the birds, they must push their heads and necks through the wire, which can result in feathers on their chests being rubbed off due to constant friction.

How big is a barren battery cage?

Contrary to popular belief, barren battery cages do not equate to one cage per bird. Rather, birds are confined in communal cages that are often no more than a few feet across, and only about 15 inches in height. In the 2017 guidelines established by United Egg Producers, an agricultural trade group for US egg farmers, each bird must have 67- 86 square inches of space. This is less space than the size of a typical sheet of paper, which is over 90 square inches. Such tight confinement means that birds cannot even spread their wings fully without hitting their cage-mates or the wire sides of the cage.

How many hens are kept in barren battery cages?

The number of hens kept in barren battery cages can vary depending on the size of the cage. Usually each one contains between four and ten birds.

Why are barren battery cages bad?

Images of industrial egg production facilities, which are essentially indoor sheds with battery cages piled on top of one another, clearly illustrate some of the reasons why this type of confinement is problematic. These environments are highly unnatural, and prevent hens from performing their normal behaviors and moving around freely. Below are a few reasons why barren battery cages are harmful.

Psychological problems

Barren battery cages prevent chickens from engaging in most of their normal behaviors, including roosting at night, perching during the day (to feel safe or to escape other birds in the flock), dust-bathing (which helps them to maintain healthy skin and feathers), fully stretching or flapping their wings, foraging and exploring (which they would normally spend large parts of their day doing), or performing their highly motivated nesting behaviors (finding somewhere quiet and secluded to lay their eggs). Barren battery cages severely restrict a laying hen’s ability to move around, rest undisturbed, and perform these normal behaviors, causing them pain, stress and frustration.

Physical trauma

Barren battery cages cause a wide array of debilitating physical conditions for chickens. The wire mesh floors of these cages can cause a host of foot disorders, including toe pad hyperkeratosis, which develops due to pressure on certain areas of the feet thanks to the sloping floors of cages. This condition can lead to painful open lesions on their feet. Overgrown claws are also common, since chickens cannot engage in ground-scratching behaviors that keep nails short naturally.

Due to selective breeding, commercial laying hens produce high numbers of eggs as compared with their wild ancestor—the red junglefowl. Commercial laying hens can produce around 300 eggs per year (mainly European production, with hens in the US averaging 285 eggs per year). This frequency leaches high levels of calcium from the skeletal system in order to produce eggshells, leading to bone fragility and to birds being susceptible to osteoporosis. In extreme cases, birds in barren battery cages may develop a syndrome called cage layer fatigue, which can cause birds to become paralyzed.

Osteoporosis

All commercial laying hens in cage and cage-free systems are susceptible to a disease called osteoporosis—a condition that weakens bones and can lead to high levels of bone fractures, as they are selectively bred to produce large numbers of eggs.

But because hens in caged systems lack the space to properly move and exercise, their bones are even weaker. Laying hens in cages are considered to have the poorest bone strength, and likely to suffer more fractures at depopulation (when they’re removed from their housing at the end of the laying period).

Forced molting

Molting is a natural, seasonal process where chickens lose and replace their feathers, and egg production is paused. Over time, a hen’s egg production decreases. In commercial breeds, this usually occurs at just over a year old. In commercial systems, hens are either killed and sold as meat around this time, or they may be induced or forced to molt to increase their egg production and extend the egg production cycle.

Forced molting can involve withholding food (this is no longer allowed in the US), or using a low nutrient feed that is freely available. Light levels may also be reduced within the barn. Forced molting halts the reproductive cycle and causes feathers to fall out and regrow. Following this, chickens begin to produce more eggs than they otherwise would. Though intended to replicate natural processes, forced molting causes stress and discomfort to chickens.

Only non-feed withdrawal forced molting methods are permitted in the US, such as changing the composition of their diet.

Which countries have banned battery cages?

In most countries, including the US, barren battery cages remain legal at a national level. However, legislation can vary based on state or regional jurisdictions, and in recent years, more countries have begun to ban or phase out these cruel systems.

Globally there are two types of cages used for laying hens: the barren or conventional battery cage (described above, and the main cage used in the US), and the so-called ‘enriched’ battery cage (also known as a furnished or colony cage). There are various legal bans relating to cages for laying hens across the world.

These are some of the countries that have banned or implemented phase-outs of cages for laying hens:

• Bhutan: Banned the barren battery cage in 2012
• The European Union (27 countries in Europe): Banned the barren battery cage in 2012, but still legally permits the enriched cage
• Germany: Banned the barren battery cage from 2010, and will ban the enriched cage from 1st January 2026
• New Zealand: Banned the barren battery cage from 2023
• Norway: Banned the barren battery cage in 2012
• Switzerland: Banned cages for laying hens in 1992

Are battery cages legal in the US?

At the federal level, there is no legislation prohibiting the use of battery cages. In February 2024, the cage-free flock represented around 40% of the total egg-laying flock in the US (in the EU, it’s about 61%, and globally, around 16%). Yet many states have begun passing their own laws to curtail the use of this type of confinement. Some of these laws have been passed in just the past few years.

The following states have passed legislation that either bans or requires the phasing-out of barren battery cages:

• Arizona (sales and production bans)
• California (sales and production bans)
• Colorado (sales and production bans)
• Massachusetts (sales and production bans)
• Michigan (sales and production bans)
• Nevada (sales and production bans)
• Ohio (production ban)
• Oregon (sales and production ban)
• Rhode Island (production ban)
• Utah (production ban)
• Washington (sales and production bans)

Cage-free vs. cages

Life on a factory farm can be difficult no matter the circumstances, but when it comes to welfare, even small improvements can make a tangible difference to animals. Cage-free systems are one such improvement for laying hens.

Cage-free can mean any loose-house system for laying hens—where birds are not confined to cages and can move around freely—whether indoor-only, or with outdoor access (e.g. free-range, pasture-raised). In the US, cage-free refers to indoor-only systems, where hens are able to walk freely within a barn containing potentially thousands of other birds. These hens may have access to perches and areas where they can engage in normal behaviors such as scratching and dust-bathing.

Globally, and even between farms, there is a lot of variation in cage-free systems, and while cage-free systems aren’t perfect, laying hens within them have the opportunity to perform their normal behaviors. They may even be able to have positive experiences—experiences that are unlikely within cages. Ultimately, the design and management of the cage-free system will play an important role in the welfare of laying hens.

What you can do to help

The animal agriculture industry prioritizes profit over animal welfare. But corporations listen to what the market wants—which is why one of the best ways you can help is by voting with your wallet. THL advocates for cutting eggs completely out of your diet if you’re able to do so. And, if you do purchase eggs, look for labels that indicate pasture-raised, free-range, or cage-free supply chains.

To join the movement to end the use of battery cages, take action with The Humane League.