How are chickens killed and do they suffer when slaughtered?

Chickens are raised for meat and eggs all over the world. Their popularity in many diets means that globally their numbers across industrial and small-scale farming operations are in the billions. The Food and Agriculture Organization of the United Nations (FAO) estimates that, in 2020, 33 billion chickens were raised in agricultural production. Around 46% of these birds are located in Asia.

Depending on the type of production and the area where they are raised, chickens are killed in a variety of inhumane ways. During their short lives from the farm to the slaughterhouse, chickens experience significant pain and suffering.

How are chickens raised?

Commercial breeds of chickens are raised for different purposes, and the particular production system they are used in determines how they are housed and raised. Over the past several decades, chicken breeds have undergone extensive genetic selection to create larger and faster-growing birds for meat. Laying breeds have been subjected to similar manipulation, resulting in much greater egg production.

Chickens used for meat and chickens used to lay eggs may be held in different housing and environments, but there are common threads across commercial chicken production. For chickens in the intensive commercial farming operations we call factory farms, these common factors include overcrowding, stress, and inhumane management practices.

Layer hens

Layer hens are chicken breeds that have been selected for high egg-laying capacity, and produce around 300 eggs per year. Once they are no longer able to lay high numbers of eggs, they are sent to be slaughtered.

Layers begin their lives in hatcheries, where male and female chicks are separated. Males are killed, and the females are kept in rearing facilities. Once they reach laying age, they are moved to a laying facility, which is often a large shed full of densely stocked wire cages called battery cages.

Eight to ten birds are crowded into each cage, with little room to move. Layer hens live their entire lives in these cages, never being able to move freely and fully stretch their wings, and leave only when they are sent to slaughter.

While other types of egg production systems exist, battery cages are the predominant form of intensive housing in the Global South, and in some countries up to 90% of hens are subjected to this confinement.

Broiler chickens

Broiler chickens are bred for fast growth and large musculature, and they are slaughtered for meat at only six to seven weeks old. Since the 1950s, the size of commercial broiler chickens has increased fourfold, not only resulting in greater meat yield but also causing debilitating health conditions for the birds. Broilers suffer from cardiovascular diseases, fluid accumulation in the abdomen, pressure sores and ulcers on their feet, lameness, and leg fractures.

Like layers, broiler chickens are also born in hatcheries and transported at around one day old to large open sheds, where they are fed until they reach slaughter weight. Over the course of their very short lives, birds usually live in overcrowded, unsanitary conditions and never get to experience the outdoors until the day they are loaded into trucks for slaughter.

How many chickens are killed each year?

Worldwide, over 72 billion chickens were slaughtered in 2019. Brazil, which makes up around 15% of the global chicken market and is the world’s largest chicken exporter, slaughtered more than 5.8 billion chickens in 2019. Brazil shares this market with the United States, which kills over 9 billion chickens annually, and China, which killed 11 billion chickens in 2019.

How are chickens treated in factory farms?

The everyday lives of chickens on factory farms are marked with cruelty and suffering. Chickens live in intensely overcrowded conditions, experience illness and injury due to breeding and rapid growth, and ongoing pain and distress from abusive management practices and untreated medical conditions.

Layer hens on factory farms have every element of their natural lives taken away from them — they are unable to forage, fully stretch their wings, move around and rest properly, dust bathe, or form normal social relationships.

A poor welfare environment may result in stress, which can make chickens more susceptible to infectious diseases. They also face intraspecific aggression from other chickens, particularly in large caged groups or unfurnished noncage systems, in the form of feather pecking and even cannibalism.

Inhumane treatment

Management practices that are cruel to chickens are routine and widely considered to be acceptable, standard practices by the poultry industry. The industry prioritizes profit and quantity of production over chicken welfare, resulting in unremitting misery for birds on factory farms.

On Brazilian egg farms, chickens are kept in cages so crowded they are unable to move at all, and suffer from diseases that go untreated. In Thailand, chickens are forced to live among excrement, egg fragments, and other dead birds. For broiler chickens, the situation is not any better — they are subjected to rough handling by workers, unsanitary conditions, wet and contaminated bedding, and physical trauma when they are transported to slaughter.

Forced molting

Forced molting is a management practice used on layer hens to cause them to start a new cycle of egg production. Hens are deprived of food for up to two weeks, during which time they lose up to 35% of their body weight and shed their feathers. This also resets their egg-laying cycle so they can produce eggs within the industry standards once food is once again offered.

When deprived of food, chickens initially increase activity and can develop aggressive behavior, but after three days activity begins to gradually reduce and birds spend longer resting, ultimately leading to a phase when the bird ceases activity. This practice is considered so cruel it has been banned in India and the European Union.

Chicks are debeaked

Debeaking is one of the cruelest practices commonly performed by chicken farmers. Debeaking removes up to two-thirds of a chicken’s beak using a hot blade or infrared radiation. In Brazil, some producers use an extreme form of debeaking called V debeaking.

Chicks are debeaked between one and eight days old. Broiler chicks are debeaked only once because they are killed before their beaks grow back, but layer hens may undergo a second debeaking if tissue regenerates.

Debeaking is not only painful when it occurs, it also causes long-term welfare problems. Chicken’s beaks are filled with sensitive nerve receptors, and debeaking is performed with no anesthesia or pain management. In addition to acute pain, chickens can experience ongoing chronic pain from debeaking in the form of painful neuromas, and malformed beaks that can prevent proper feeding as well as the grooming and preening important for feather and skin health. Debeaking also results in severe burns to the tongue, nostrils, and oral cavity.

Confinement in battery cages

Battery cages are communal cages where birds are kept intensively. They provide around 500 square centimeters of space per hen — or the equivalent of a sheet of paper. Laying hens are held in battery cages for their entire lives, with profound consequences for their welfare.

Constant near-immobilization may lead to abnormal behaviors, like aggression and feather pecking. Hens experience constant frustration and distress due to their inability to perform behaviors essential for their wellbeing, including nesting and perching. The lack of physical activity affects their health as well, causing osteoporosis and foot conditions.

Genetic manipulation

Birds raised for meat consumption suffer from several metabolic conditions and abnormalities that impact their welfare and lead to increased rates of illness and death. The heavy muscle weight of broilers relative to their bone structure stresses their cardiovascular systems, and birds suffer from cardiovascular diseases like heart arrhythmias and sudden death syndrome.

Ascites, or the build-up of fluid in the abdominal cavity, is a common problem caused by the metabolic demands of fast growth and the decreased ability to oxygenate the blood. This leads to pulmonary hypertension, heart failure, and subsequent fluid buildup, which compromises respiration and causes distress and pain in the birds.

Broiler chickens also have difficulty walking because of their fast growth, and may become immobile due to lameness — leaving them at risk of dying from dehydration when they cannot access water.

Light management

Most chickens on factory farms never see the light of day and are kept indoors their entire lives, although some farms in countries including Brazil may use partially open sheds that allow some natural light. However, the use of artificial lighting to manipulate chicken behavior and physiology is a common management tactic in the poultry industry.

Producers use light of varying intensity, spectrum, and duration to stimulate hormone production in chickens. The purpose of this is to cause chickens to mature faster, induce ovulation, and increase egg weight and egg production. Broiler chickens raised in continuous dim lighting experience greater incidences of eye and lens damage, increased fearfulness, and higher rates of leg disorders.

High levels of ammonia

Ammonia is a toxic gas created by the decomposition of nitrogen in animal waste. On factory farms, chickens are often kept in unsanitary sheds and cages with poor ventilation, where waste buildup leads to high levels of ammonia. If waste is not removed and the area cleaned, ammonia can reach toxic levels.

Evidence indicates chickens find ammonia aversive, and being subjected to constant high levels significantly impacts their well-being and health. Birds exposed to ammonia develop lesions in the respiratory tract and eye inflammation. Exposure also affects their immune systems, making them more susceptible to respiratory ailments and infections.

What are the four steps in slaughtering chicken?

A chicken’s journey to the slaughterhouse is marked by painful and distressing events. Chickens are often transported for days, deprived of food and water, and subjected to extremes of cold and heat. In the case of broiler chickens, the process of catching them and packing them into crates to be taken to slaughter often results in injury and trauma.

Once chickens arrive at the slaughterhouse, they go through four stages. Given that billions of chickens are killed each year, pain and suffering during slaughter raises pressing welfare concerns.

1. Stunning

Birds are first stunned before slaughter. Methods for stunning vary, but two common methods are to use a gas, like carbon dioxide, or electrical water baths. For gas stunning, birds in crates are moved into a gas chamber and exposed to high levels of carbon dioxide. This causes distress and likely pain, as well as seizures often violent enough to dislocate joints. If there is a long duration between stunning and slaughter, chickens can regain consciousness.

When electrical water baths are used, chickens are removed from crates and forcibly hung upside down in leg shackles. These actions are performed rapidly by workers, resulting in frequent injuries to birds like leg and wing fractures. Heads and toes can also become trapped, resulting in injury and traumatic amputations when chickens are pulled from the crates. Electrical stunning sends a painful current through the chickens’ bodies, causing tissue damage, seizures, and broken bones.

Stunning is intended to render chickens unconscious, however, decades of research on the welfare aspects of electrical water bath stunning reveal disturbing concerns. Birds may miss the water bath and enter slaughter fully conscious, fail to receive enough current to be rendered unconscious, or experience painful pre-stun shocks. In many cases, birds may appear to be paralyzed from stunning but in fact remain conscious.

2. Slaughter

After stunning, chickens are killed. Generally, the throats of birds are cut, either mechanically or by workers, and they bleed to death. If stunning was ineffective, chickens suffer significantly from the pain and distress of being killed in this way. If the arteries in the neck are partially cut, birds face prolonged deaths. In studies of birds slaughtered without prior stunning, chickens remained conscious for up to 60 seconds as they were bleeding out.

3. Plucking

After their throats are cut, chickens are dumped in vats of scalding water to facilitate feather removal. If stunning was incomplete and chickens have not fully exsanguinated before this step, they may be scalded alive.

Next, chickens’ bodies are plucked of feathers, which may be performed by machines, and then they are moved on for further processing.

4. Eviscerating

In this final step before packaging and preparation for sale, the internal organs and feet of chickens are removed and their bodies are washed.

How are chickens killed?

Chickens are killed in different ways, depending on their life stage and local practices.

Gas

Controlled atmosphere stunning can be used to kill chickens, by subjecting them to low atmospheric pressures. Generally a mixture of gases is used, like argon and nitrogen, to create an oxygen-deprived atmosphere.

Electrical stunning

Electrical stunning is not commonly used as the sole method of slaughter, although higher frequencies can induce cardiac arrest in birds. Nevertheless, this is generally a stunning method.

Throats cut mechanically

In many slaughterhouses, chickens pass through a machine that cuts their throats while they are hanging upside down in shackles. This method risks missing chickens, who may regain consciousness after being stunned and end up being boiled alive as they move down the slaughter line.

Grinding up chicks alive

In the egg industry, male chicks are considered waste products and are killed in many inhumane ways, including by suffocation and being ground alive in large mechanical shredders.

Do chickens feel pain when slaughtered?

Chickens possess a highly developed nervous system and experience pain when injured and killed. Chickens also have complex cognitive and emotional capacities, which result in emotional distress and suffering during slaughter.

Multiple steps in the slaughter process cause pain to chickens, from being deprived of food and water for days and subjected to extreme cold and heat during transport, to rough handling and restraint that lead to traumatic injuries.

Stunning procedures do not guarantee unconsciousness and common methods cause distress and pain to chickens. When chickens are improperly stunned, they experience the agony of slaughter while fully awake and sensible.

Are chickens humanely slaughtered?

Billions of chickens pass through slaughterhouses every year, which focus on speed of processing over chicken welfare. With so many chickens moving through the slaughter line, there is a higher risk of trauma as birds are handled and restrained, as well as a greater likelihood of incomplete stunning or slaughter.

Given the massive numbers of chickens being killed and the painful and distressing practices used to kill them, chickens are not humanely slaughtered.

Conclusion

Chickens raised for eggs and meat experience pain and suffering throughout their unnaturally shortened lives. One of the best ways to help chickens who are suffering in the poultry industry is to stop consuming them.