The welfare concerns arising from 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 battery cage is and why it is so harmful.

What is a battery cage?

A battery cage, sometimes called a conventional cage, is designed to house laying hens, meaning female chickens who produce eggs. After being born in hatcheries, undergoing the process of debeaking, and awaiting maturity (which usually takes about 18 weeks), hens are sent to the battery cages where they will spend the remainder of their lives, which generally last for about two years.

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Each cage contains between four and ten birds.

While designs may differ based on country or individual farm, generally battery cages are 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 mesh, which can result in feathers on their chests being rubbed off due to constant friction.

How big is a battery cage?

Contrary to popular belief, battery cages do not equate to one cage per bird. Rather, birds are stuffed into 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, a marketing association of US egg farmers, each bird must have 67-86 square inches of space. People sometimes compare this to the size of a typical sheet of paper, which is actually even bigger: 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 battery cages?

The number of hens kept in battery cages can vary depending on the size of the cage. While space per bird is more strictly enforced, the size of the cage itself is less so. Cages can range from the size of a bathtub to the size of a desk drawer. Usually each one contains between four and ten birds.

Why are 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, more closely resembling prisons than farms. Below are a few reasons why battery cages are harmful.

Psychological problems

Battery cages prevent chickens from engaging in most of their natural behaviors, including perching, roosting, dust-bathing, foraging, and exploring. It is nesting behaviors, however, that stand out as being particularly harmful to suppress in hens. Under normal circumstances, hens search out private places in order to construct nests before laying eggs. In battery cages, these desires are stifled, manifesting instead as repetitive stress-induced behaviors (such as pecking at other chickens); general restlessness; or “vacuum” nesting, where a hen essentially mimes creating a nest.

Given that laying hens can be compelled to produce eggs 300 days out of the year, this frustration is ongoing and a serious welfare concern.

Physical trauma

Battery cages cause a wide array of debilitating physical conditions for chickens. The wire mesh floors of battery 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 genetic engineering and selective breeding, the bodies of hens are compelled to produce unnaturally high volumes of eggs as compared with populations in the wild, or those living in extensive agricultural conditions. This frequency leeches high levels of calcium from the skeletal system in order to produce eggshells, leading to bone fragility. In extreme cases, a syndrome called cage layer fatigue may develop, whereby birds can become paralyzed by calcium depletion combined with spinal collapse from their inability to properly stretch, walk, or stand up. Unable to reach water spouts, they slowly die from thirst.

4 Tiers 100-300 Birds Capacity Chick Brooder Cage 

Forced molting

Molting is a natural, seasonal process occurring once a year with the onset of winter, when chickens consume less food, replace their feathers, and produce fewer eggs. This decrease in egg production is unacceptable to industrial producers, so birds are either killed and sold as meat, or a forced molt is conducted.

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Hens are denied food and water to force them to produce more eggs.

Forced molting involves withholding food, water, or both from chickens for a period of time, along with decreasing the hours of light within the barn. This starvation period halts the reproductive cycle, reduces body mass, and causes feathers to fall out. After the starvation period, chickens begin to produce eggs at even higher rates. Though intended to replicate natural processes, forced molting causes stress and discomfort to chickens.

Light manipulation

Because the number of daylight hours affects egg production in laying hens, light can be manipulated to artificially induce birds into ramping up production. Hens' bodies are attuned to reach maximum egg-laying capability when there are 16 hours of daylight during summer, and in springtime at 14 hours per day. Industrial egg production facilities often provide artificial light in order to mimic a full 16 hours of daylight for as much of the hen’s life as possible.

Osteoporosis

Osteoporosis can be caused by a lack of adequate movement and exercise, and it's a common ailment among many species of captive animals, including elephants. In caged hens, this degenerative disease is a widespread problem. The inability to walk more than a few paces, to run, or even to properly stretch their wings leads to bone fragility and fractures, especially during transport.

Which countries have banned battery cages?

In most countries, including the US, 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 outlaw or phase out these cruel devices. These are some of the countries that have nationally banned or implemented phase-outs of battery cages:

• Bhutan: Banned in 2012
• The European Union: Phase-out completed in 2012
• Germany: Phase-out completed in 2006
• India: Phase-out completed in 2017
• New Zealand: Phase-out to be completed in 2022
• Norway: Banned in 2012
• Switzerland: Banned in 1992

Are battery cages legal in the US?

At the federal level, there is no legislation prohibiting the use of battery cages. A 2017 United Egg Producers report estimates that 85 percent of commercial egg production in the US uses battery cages, compared with 90 percent globally. 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 battery cages:

• California
• Colorado
• Massachusetts
• Michigan
• Ohio
• Oregon
• Rhode Island
• Utah
• Washington

Other examples of caged animals

Many other species of animals endure extreme caging on factory farms. Among the most concerning in terms of welfare violations are gestation crates, in which female pigs who are used for breeding, known as sows, are kept for much of their lives. These crates tend to be roughly the size of the sow’s body, preventing her from even turning around. Cows on dairy farms can also endure extreme confinement when they are tethered to stalls for the duration of their lives, unable to walk on grass or go outside.

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Female pigs are kept in cages roughly the size of their bodies.

Even farms used to produce products other than food, such as fur, often make use of small, battery-style cages. Mink farms are common in many countries, and in 2020 came under fire after certain farms became potential zoonotic transmission hotspots for new strains of coronavirus, leading to millions of minks being killed in order to reduce the risk.

Cage-free vs. battery cage eggs

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 small improvement for laying hens. Cage-free hens are able to walk freely within a barn containing potentially thousands of other birds. While not permitted to go outside, these hens usually have access to perches and areas where they can engage in natural behaviors such as scratching and dust-bathing. While still a far cry from a natural or happy existence, a cage-free life is significantly more humane than one spent in a battery cage.

What you can do to help

The animal agriculture industry prioritizes profit over animal welfare at all times. 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. Cut eggs completely out of your diet if you’re able to do so. And, if you must 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.