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March 13, 2023

8 min read

Broiler chickens: Who are they and how long do they live?

Photo: Lukas Vincour / Zvířata Nejíme / We Animals Media

Modern-day chickens raised for meat, called “broilers,” are a far cry from chickens just a few decades ago. They consume less food, grow more quickly, and reach a much larger size. The way that chickens are farmed  for their meat today is the result of intense breeding programs that were kickstarted with a contest run by a grocery store in the mid-20th century. As a result of all the ingenuity and invention that has gone into their genetics, chickens suffer immensely during their short lives, and today’s massive scale of chicken production wreaks havoc on the environment.

Broiler chicken history

Up to the early 20th century, chickens were “dual purpose” and raised primarily in backyards to supply both eggs and meat to their caretakers and communities. Unlike today, there were not two separate types of chickens, one for laying eggs and one for meat. This differentiation started in the 1920s but really took off in 1945 due to the “Chicken of Tomorrow” contest organized by the USDA and sponsored by the grocer A&P, which awarded prizes to the flocks that were judged as having the best meat, most efficient feed conversion ratio, and highest growth rate. In order to win, farmers started breeding the largest male and female chickens together, to increase the size of their offspring. The contest enabled the broiler breeder companies that we know today, such as Cobb, Vantress (now collectively Cobb-Vantress), and Hubbard to establish themselves.

By the 1980s and early 1990s, producers were using ever more sophisticated techniques to breed the fast-growing chickens found on farms today—chickens that consume less food but grow larger and faster than birds just 40 years ago. Within less than two generations, chickens raised for meat went from birds pecking around in a neighbor’s backyard to being packed into warehouses by the thousands, unable to naturally breed without being starved.

What birds are considered broiler chickens?

Broiler chickens are those which are raised for their meat. Today there are two companies that control the genetics of most broiler chickens: Aviagen and Cobb-Vantress. Aviagen has bred the Ross line of chickens, which they boast “is the world’s number one broiler breeder brand.” Meanwhile, Cobb-Vantress boasts that their premier line of broiler chickens, the Cobb, is “the world’s most efficient broiler.” Regardless of which line an individual chicken is born from, they experience great suffering that is directly caused by the intense breeding that has taken place in the very recent history of their family tree.

Broiler chicken characteristics

Broiler chickens share a variety of common characteristics. Visually they sport almost universally white feathers. Looking past their physical appearance, however, you can also find a number of similarities in their health and even genetics. When it comes to the actual genetic makeup of broiler chickens, they are all very similar, placing them at a greater risk of disease transmission. On the health front, because of their swift growth rate, broiler chickens are likely to develop a range of issues such as ascites and sudden death syndrome.

What’s the difference between broiler and layer chickens?

Though just a few decades ago chickens were raised for both their meat and the eggs they would lay, today there are specific breeds intended for each purpose. Broiler chickens, those raised to be slaughtered for their meat, grow very large, very quickly. These chickens are usually slaughtered at about seven weeks old in the United States, by which time they have already grown to be about 6.5 pounds. Laying hens, on the other hand, typically live for about 72 weeks before their production drops and they are slaughtered. During peak production they may lay 300 eggs or more a year.

Why are they called broiler chickens?

Broiler chickens, also called “broiler-fryers,” originally got their name from a preparation method common for their meat due to their young age and their more tender flesh. When chickens are slaughtered at an older age, they may be called a “roaster.”

Broiler chicken farming

The reality for Modern broiler chicken farmers are often locked into predatory contracts with large corporations, competing against other farmers to produce the heaviest chickens with the least amount of feed. The farmers that don’t come out on top often struggle to get by, as the corporations require increasingly expensive upgrades to the farm facilities. Much of the poultry industry is run as a “tournament system,” where producers compete against their neighbors and pay is based in part on how much you produce compared to others in your area. This system has left many chicken farmers deeply in debt and has been widely criticized by farmers as predatory.

Will broiler chickens lay eggs?

Historically, chickens eaten for their meat were often from the same dual-purpose breed as laying hens. Even breeds raised primarily for meat, like the Barred Rock, produced edible eggs. Yet if left to their own devices, modern broiler chickens would quickly cease to exist because they are not able to breed without human intervention. Broiler chickens have been bred to rapidly grow to sizes far beyond the range of the chickens raised for food even a generation ago. Birds bred for fast growth lead to medical complications that make breeding, laying eggs, and even living long enough to reach maturity difficult. The birds used to breed broiler chickens need to have their feed restricted to avoid growing to a size that would stop them mating and laying, which means that they live in a state of constant hunger induced by their genetics.1

How long does it take to raise a broiler chicken?

According to the National Chicken Council, modern broiler chickens are slaughtered at an average of 47 days old, having already reached a weight of about 6.5 pounds. They consume about 1.8 pounds of feed for each pound of weight they gain. The modern rate of growth is much faster than it was in 1940, prior to the “Chicken of Tomorrow” contest that launched the genetic modification of chickens via breeding into full swing. In 1940, chickens were slaughtered at an average age of 85 days, having reached about 2.9 pounds, and after consuming approximately 4 pounds of feed for every pound of weight gained.

How long does it take for a broiler chicken to mature?

Broiler chickens are not mature when they are slaughtered at an average age of just 47 days, or less than 7 weeks old. In fact, for Cobb chickens puberty doesn’t even start until they are 12 weeks old. Between 16 and 20 weeks they are in their “grower phase” in which hens increase their weight by a third and reach maturity.

How long do broiler chickens live?

The average broiler chicken is slaughtered at 47 days old. Without very particular care and feed withholding, the likelihood of mortality due to health problems related to their growth or genetics increases from that point onward.

Broiler chicken side effects

Modern broiler chickens are touted by the industry as being extremely efficient “products” within the food system. This level of efficiency comes at great cost, for the birds themselves and the environment as well.

Welfare issues


Overcrowding is a huge difficulty for many broiler chicken barns. Such a living situation leads to an increase in inflammation and a decrease in macrophage activity, making the birds more susceptible to disease.2


For transport to the slaughterhouse, birds are routinely stuffed into crates alongside other birds before the crate is loaded onto a truck. This practice leads to painful bruising, dehydration, and even death.


Once chickens have reached the slaughterhouse, they are killed. Often this process is rushed and rough due to workers being required to move through the process quickly. As a result, birds endure immense suffering, such as not being stunned before slaughter, or even not being slaughtered before they are drowned in scalding hot water.

Bird health issues

Cardiovascular dysfunction

Due to their fast growth, broiler birds often experience heart problems, because their hearts are unable to meet the demands of their bodies.

Integument lesions

Overcrowding is one of the main causes of skin lesions in broiler chickens. This is due to a greater incidence of trampling when seeking food and water. Another source of skin lesions is aggression between chickens.

Ocular dysfunction

Chickens have very sensitive eyes and rely heavily on their sight. The high levels of ammonia in chicken barns can lead to painful conditions such as conjunctivitis, damage to the cornea, and swelling of their eyelids.3

Skeletal dysfunction

A number of different skeletal disorders can be found in broiler chickens, including leg deformities and deformities of the spinal column. Many of these conditions are caused by the swift growth of the birds.

Environmental issues


Ammonia, which contains nitrogen, is released in the droppings of the thousands of chickens housed in broiler factory farms. This nitrogen can ultimately enter waterways and have serious effects on the health of aquatic ecosystems, causing algal blooms and creating dead zones with depleted oxygen levels.

Greenhouse gas emissions

The chicken production sector, including both eggs and meat, releases 0.6 gigatonnes of carbon dioxide-equivalent greenhouse gases every year. This accounts for 8 percent of emissions from the entire animal agriculture sector.


Estimates suggest that the poultry farms in North Carolina alone produce five million tons of waste every year, threatening the air and water quality of the surrounding area due to the high levels of nutrients such as nitrogen and phosphorus the manure contains.

Broiler chicken facts

  • The broiler chicken industry is highly vertically integrated, with about 30 companies controlling the entire process from raising to processing the birds.
  • Chickens have an extra type of cone in their eyes that allows them to see ultraviolet light that we cannot.
  • Virtually all chickens have been genetically modified.
  • The United States is currently experiencing one of the most severe avian flu outbreaks in our history with over 52 million farmed poultry impacted.
  • Some farmers that once raised chickens are moving away from the industry and toward raising plants or fungi, such as mushrooms, instead.


The impact that raising chickens has on the environment and the birds themselves is deliberately hidden from the general public by the massive, integrated corporations that make up modern broiler chicken farming. They control everything from how the birds are raised to how they’re transported and slaughtered, and even how they’re marketed to consumers. One common tactic that they employ to make consumers feel at ease when purchasing chicken is humanewashing, in which they use the packaging to suggest that the chicken had a peaceful, healthy life, a far cry from the reality on factory farms.



Laura M. Dixon et al., “The Effects of Feed Restriction, Time of Day, and Time Since Feeding on Behavioral and Physiological Indicators of Hunger in Broiler Breeder Hens,” Poultry Science 101, no. 5 (May, 2022)


A. V. S. Gomes et al., “Overcrowding Stress Decreases Macrophage Activity and Increases Salmonella Enteritidis Invasion in Broiler Chickens,” Avian Pathology 43, no.1 (2014): 82–90,


I. U. Sheikh et al., “Ammonia Production in the Poultry Houses and its Harmful Effects,” International Journal of Veterinary Sciences and Animal Husbandry 3, no. 4 (2018): 30–33,