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Battery cages: What are they, why are they bad, and are they legal in the U.S.?

Photo: Jo-Anne McArthur / We Animals Media

Consumers have been increasingly interested in moving toward cage-free egg production systems. Yet despite the efforts of advocates and consumers alike, 70 percent of laying hens still spend their lives in battery cages. The lives of these birds are blighted by the system of chicken farming in which they are raised. Having been selectively bred to produce as many eggs as possible using techniques that were only recently developed, they are condemned to suffer various health complications regardless of the housing in which they are kept. Yet battery cages are a further cause of suffering for the birds, employed just so that corporations can turn a slightly higher profit, with no regard for animal suffering.

What are battery cages?

A battery cage, or conventional cage, is a type of small metal enclosure commonly seen on farms raising laying hens. Each cage confines several chickens in very close proximity with one another. The floors of the cages are sloped so that when an egg is laid it rolls out of the cage into a trough. Hens housed in battery cages spend almost all of their lives in the cage, which prevents them from taking part in natural behaviors such as dust bathing, foraging, or even walking. In battery cages, hens also demonstrate fewer pleasure behaviors such as wing flapping and tail wagging. Unwanted behaviors such as feather pecking are common in cages because the barren environment encourages frustration and aggression. Some types of battery cages may cause injury to hens who can get stuck in the wiring.

In recent years, there has been a large amount of pressure on factory farms raising laying hens from both animal rights and welfare organizations to move away from battery cages and toward cage-free or pasture-raised housing systems.  These efforts have resulted in many farms phasing out their battery cages. Tireless advocacy also resulted in the European Union effectively banning the use of barren battery cages via legislation first enacted in 1999, though only fully implemented some years later.

Why are they called battery cages?

When we say “battery” we most often mean the power source in our television remotes or smartphones, but there are other meanings of the word as well. In the context of battery cages, the word means “a number of similar articles, items, or devices arranged, connected, or used together.” Inside each of the barns on a factory farm raising laying hens in battery cages, hundreds or even thousands of cages can be found connected together in long rows.

What does a battery cage do?

There are a few different reasons why battery cages have been used for housing laying hens. Industry leaders claim that the cages prevent the spread of harmful behaviors such as aggressive feather pecking and cannibalism—though battery cages ensure that certain birds will suffer the pecking their entire lives. Other stated reasons include slowing the spread of pathogens and minimally improved air quality due to an absence of litter. At the root of any industry rationale their use, however, is that battery cages allow companies to make more money.

The cost of battery cages paid by the laying hens is high. Though the cages may limit the proliferation of feather pecking and the deaths that can result from bullying behavior, the cages lock some hens into that dismal reality. The tendency toward feather pecking within battery cages leads producers to debeak chickens as a standard practice; this debeaking, lately renamed “beak trimming,” involves the removal of one quarter to one third of the beak in a painful procedure that often leads to neuromas and ongoing suffering. The lack of litter on the floors of the metal cages can lead to painful foot injuries.

How big is a battery cage?

Battery cages are made by many different companies and in a variety of slightly different styles and sizes based on how many chickens they are intended to hold. One company producing battery cages offers a standard layer cage that is 24 inches wide and 25 inches deep with a height that goes from 17 inches at the front of the cage to 14 inches at the back. They suggest placing nine hens into each of these cages, leaving only 67 square inches of space per bird. This is less space for each hen than she would get if she spent her life living on a single standard sheet of printer paper.

How many hens are kept in a battery cage?

The number of hens housed in an individual battery cage varies based on the size of the cage, how many chickens are resident at a given time, and laws that may apply in that farm’s jurisdiction, if any. Instead of governing how many chickens can be housed in a single cage, Oregon requires that hens have a minimum of 67 square inches of space for white leghorn chickens and 76 square inches of space for brown egg layers. Cage manufacturers may offer a suggested number of birds to be housed in the cages they create. The company Ford Dickinson Inc. suggests keeping 9 laying hens in each of their standard layer cages. This provides each bird with 67 square inches of space. A standard sheet of printer paper has an area of 97 square inches.

Why are battery cages bad?

There are numerous reasons that battery cages and the factory farms that use them are destructive, beyond the limited amount of living space that they provide for hens. The industry as a whole causes a huge amount of suffering simply by breeding the hybrid birds who provide meat and eggs, but battery cages take that physical and mental suffering to another level. The factory farms on which the birds are raised also wreak huge damage on the environment and the major players keeping the industry running in this harmful way face little accountability for their actions.

Physical trauma

Physically, battery cages are extremely restrictive and prevent hens from engaging in most of their natural behaviors. Because feather pecking, which can lead to cannibalism, commonly develops in caged hens, beak trimming is standard practice at many farms. The procedure can lead to chronic and acute pain due to nerve injury and tissue damage.

Psychological problems

The lifelong confinement and lack of ability to exercise or express their natural behaviors can lead to abnormal behaviors in hens in battery cages. Examples of such abnormal behaviors include feather pecking and cannibalism.

Forced molting

Ordinarily, laying hens would be considered useless after only a single year of production because the number of eggs they lay drops significantly. In an effort to maintain their profits, the industry has instead begun “forced molting” after the first year. Forced molting is achieved by withholding food and water, causing the hens to stop laying eggs and lose their feathers for a short period of time. Once the birds are being fed again the eggs are larger and better quality. However, the process of forcing a molt is extremely stressful for the birds and can lead to increased pecking of cagemates and increased mortality during the molting.

Light manipulation

Manipulating laying hens to produce more eggs using light is a longstanding norm within the egg industry. Producers employ lights of specific colors, exposures of different durations, and differing types of light in order to maximize the number of eggs that a hen produces.1 Egg farmers make these efforts to increase production despite the health issues that are caused by the hens’ high rate of egg laying, such as osteoporosis.


Laying hens are prone to develop osteoporosis because of the strain that producing a large number of eggs places on their body, using a large amount of calcium that would otherwise strengthen the birds’ skeletons. Hens kept in battery cages face additional bone fragility simply from a lack of exercise. This leads to broken bones and is responsible for a third of all deaths in hens housed in battery cages.

Damage to the environment

Factory farms housing chickens in battery cages often raise thousands of individual chickens at any given time. As the chickens age and are no longer considered profitable, they are replaced by new layers with higher production rates, who can make a greater profit for the industry. Every dozen eggs produced contributes 2.7 kilograms of carbon dioxide-equivalent gases into the atmosphere—the equivalent of charging a smartphone 328 times.

Are battery cages legal in the U.S.?

Battery cages are federally legal in the United States. However, more and more states are banning battery cages or mandating that laying hens be raised in cage-free systems. Chickens raised for egg production purposes in Oregon will all be cage-free by 2024 per a law signed by the governor in 2019. Just a couple of years later in 2021, the governor of Utah signed a similar measure calling for laying hens to be raised cage-free by 2025.

What countries have banned battery cages?

Several countries have banned battery cages due to concern for the welfare of laying hens. The ban on traditional battery cages in the European Union, which includes 27 countries in Europe, went into full effect on January 1, 2012. However, the ban does allow for so-called “enriched cages” that have more space per bird and opportunities for activities such as perching. Australia also recently took steps to phase out battery cages by 2036. While this represents a certain degree of progress, even cage-free eggs usually come from animals languishing in factory farms in low welfare conditions.


Battery cages have long been a staple of the egg industry, leading to profound suffering for the laying hens. Though consumers and advocates have pushed back on this standard for years and have achieved several wins and a clear international movement toward cage-free systems of production, the reality is that as long as hens are forced to lay hundreds of eggs a year they will continue to suffer.



Ashley England, and Isabelle Ruhnke, “The Influence of Light of Different Wavelengths on Laying Hen Production and Quality,” World’s Poultry Science Journal 76, no. 3 (July, 2020): 443–458,