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Growing Meat Chickens

This extensive web page covers all aspects of meat chicken farming, from the arrival of the one-day old chicks from the hatchery at the farm to when the birds reach the market weight.  The various sections can be accessed directly by clicking on the relevant heading in the listing below:

Broiler Farm

Most commercial meat chicken farms are intensive, highly mechanised operations that occupy relatively small areas compared with other forms of farming.

Commercial broilers are run on litter (e.g. rice hulls, wood shavings) floors in large poultry sheds. THEY ARE NOT KEPT IN CAGES in all of the production systems used in the  industry.  The main production systems are generally referred to as conventional, free-range and organic.  For a simple comparison of these systems, click here.

Hatchery to farm

Chicks are transported from the hatchery to broiler farms, usually in ventilated chick boxes in specially designed, air-conditioned trucks. Although the remains of yolk sac taken into its abdomen at hatching contains nutrients and moisture to sustain the chick for up to 72 hours, it is important that chicks receive warmth, feed and water within a reasonable time of hatching.


Meat chickens are farmed in large open poultry houses, usually refered to as ‘sheds’, ‘houses’ or barns, but sometines as ‘units’. Shed sizes vary, but a typical new shed is 150 meters long and 15 meters wide and holds about 40,000 adult chickens. The larger sheds can contain up to 60,000 broiler chickens. There are often three - ten sheds on the one farm. A typical new farm would house approximately 320,000 chickens, with eight sheds holding approximately 40,000 chickens/each.

Traditionally, broiler sheds in Australia have been ‘naturally ventilated’, with the sides of the shed open to fresh air. The amount of air circulating through the shed is changed by raising/lowering curtains running along the side of the shed, or by a vent opening at the top of the shed. Fans encourage air flow, and water misting systems cool birds by evaporative cooling in very hot conditions.

An increasing number of chicken sheds in Australia have ‘tunnel ventilation’. Tunnel ventilation sheds have fans at one end of the shed which draw air into the shed through cooling pads in the walls, over the chickens and out the fan end of the house at high speed. Three or four temperature sensors in the poultry house allow the fan, heating and cooling settings to be adjusted as often as every three minutes.

Feed lines and pans run the length of the shed and are supplied automatically by silos from outside. Water lines run the length of the shed, with drinkers at regular intervals. Water and feed are placed so that chickens are never more than about 2 metres from food and water. 


Broiler chicken drinking from a nipple drinker

Chicks at a feed pan

Rearing the chickens

  • Spreading a thick layer of clean and fresh litter, such as sawdust, wood shavings or other material such as rice hulls across the floor for bedding for the bird.

  • Preheating the shed

  • Checking feed and water systems.

On arrival at the broiler farm, day-old chicks are placed onto the floor of the shed, where they are initially confined to an area of between a half to one third of the total shed area (the ‘brooding area’) and given supplementary heating from gas heaters or heat lamps. This is called brooding and the heaters are referred to as brooders. Extra feed pans and water dispensers are provided in the brooding area, and the bedding may be partly covered with paper to stop dropped feed from getting into the bedding and spoiling.

Both male and female chicks are reared as meat chickens. While the flocks are usually of mixed sex, some operations may grow male and female chickens separately, depending on market requirements. For example, one company grows out only male chickens in one area, allowing its operations and processing plant in that area to be geared up specifically for larger birds, while sending female chicks to another area.

Broiler shed after arrival of day-old chicks


For the first two days of the flock’s life, the shed temperature is held at 31 - 32ºC, the optimum temperature for baby chick comfort, health and survival.

As the chickens grow, they need less heat to keep them warm, so the temperature of the shed is gradually lowered by about 0.5°C each day after the first two days, until it reaches 21 - 23°C at 21 days. The farmer aims to maintain shed temperatures within this range, although in sheds of large birds towards the end of grow-out, the temperature may be reduced.

Shed temperature and humidity can be managed by altering ventilation and using stirring fans and water mists. Air quality is also managed by varying shed ventilation.

Depending upon ambient conditions, the brooders will be removed at some time between 4 and 14 days.

As the chickens grow, the area available to them is increased until they have free run over the floor of the entire shed.

Generally, feed and clean water is available 24 hours a day, although some operators make feed available at specific 'meal times' only. This practice may stimulate better digestion, improve bone strength and prevent birds from becoming over fat. For further information on what chickens are fed, see Feed.

The chickens have adequate lighting to see by and to find feed and water, with dark periods each day to allow them to rest. The lighting provided is usually dimmer than natural lighting to promote calm.

Shed temperature, humidity and air quality are checked and adjusted regularly, either manually by the farmer or automatically by computer controllers.

The farmer also checks his flocks regularly to monitor the flock’s health and progress, remove any dead birds, and cull any sick or injured ones. Farmers also check feeders and waterers. Careful management of ventilation and waterers helps keep the litter clean and dry, as poor litter affects air quality and can affect bird health and performance.

Over the life of the broiler flock only about 4% of chickens are lost. This is through natural causes or selective culling.

Harvesting the meat chickens

In Australia, a percentage of chickens are harvested from most flocks on several occasions. Harvesting, also known as ‘partial depopulation’, ‘thinning out’, or ‘multiple pick-up’, may be done up to four times, depending on need for light or heavy birds. Thinning out sheds allows more space for the remaining birds and reduces the natural temperatures in the shed.

The first harvest might occur as early as 30-35 days and the last at 55-60 days.

Chickens are often harvested at night as it is cooler and the birds are more settled. They are generally picked up by specialised contract ‘pick-up’ crews under low lighting conditions so that they are calm and easy to handle. They are usually caught by hand and placed into plastic crates or aluminium modules designed for good ventilation and safety from bruising during transport. These crates or modules are handled by specialist forklift equipment and loaded onto trucks for transport to the processing plant.


When all the birds have been removed from the shed (after about 60 days), it is cleaned and prepared for the next batch of day old chickens.

The next batch generally arrives in five days to two weeks, giving time to clean the shed and prepare for the next batch. The break also reduces the risk of common ailments being passed between batches as many pathogens die off.

Many farms undertake a full cleanout after every batch. This includes removing bedding, brushing floors, scrubbing feed pans, cleaning out water lines, scrubbing fan blades and other equipment, and checking rodent stations. High pressure hoses clean the whole shed thoroughly. The floor bases are usually rammed earth and because low water volumes are used, there is little water runoff.

The shed is disinfected, using low volumes of disinfectant which is sprayed throughout. An insecticidal treatment may be applied in areas where shed insects such as beetles are a problem and may threaten the next batch. Disinfectants and insecticidal treatments must be approved by the Australian Pesticide and Veterinary Medicines Authority as safe and fit for use in broiler sheds.

Company veterinarians or servicemen may test sheds after a full cleanout to confirm sheds have been adequately cleaned and potential disease agents removed.

On other farms, a partial clean up of the shed is done, including removing old litter and/or topping up fresh litter and cleaning and sanitising equipment. A full cleanout is done after every second or third batch of chickens.

Number of Batches a Year

As each broiler flock spends 6-7 weeks in a shed and there is a two week break between batches, farmers run about 5.5 batches through a shed each year.

Farm Biosecurity

Farmers take precautions to prevent entry of diseases onto broiler farms.

People can carry disease on their footwear, clothing, hands and even vehicles, so growers take steps to minimise the risks they pose. These may include:

  • signage and gates at access points to the farm to discourage unauthorised entry
  • requirements for visitors and service providers to wear overalls and boots provided by the farmer
  • disinfecting footwear in foot washing baths at the entrance of each shed
  • minimising vehicle movements, and requiring vehicles or equipment that have visited other farms to be washed down 
  • scheduling movements so that where people or vehicles must go between farms on the same day without a thorough disinfection, the youngest flocks are visited first and the oldest last.
  • As wild birds can carry disease, keeping birds and their droppings away from chickens is important. Prevention measures include:
  • netting the sheds so they are wild bird proof
  • not allowing farmers and their employees to keep birds of any type including budgies or parrots as pets
  • cleaning up spilled feed promptly to discourage visiting birds
  • where practical, not having dams that would attract water birds
  • sanitising chicken’s drinking water if it could be contaminated by wild birds (eg dam or river water).
  • Farmers have documented pest control programs to reduce the risk of diseases being carried on to the farm by rodents.

Strict records are kept by the farmer of the chickens’ health, growth and behaviour, so that any emerging disease problem can be identified rapidly and acted upon.

Growth Rates

A number of factors affect the chickens’ growth rate and size at harvest. These include:

  • Breed
  • Age at harvest
  • Feeding regime
  • Gender (males grow faster)
  • Age of parent flock (ageing flocks produce bigger eggs and the chicks from larger eggs grow faster)

Why do chickens grow to market weight so quickly?

Most of the improvement in growth rates over the last 50 years ago is due to improved breeds of chicken. This genetic gain, which has been achieved through conventional selective breeding, is due to:

  • investment in advanced breeding programs by the large well-resourced specialist breeding companies overseas
  • the number of generations that can be produced in a relatively short period of time. Chickens reach sexual maturity at about 20-25 weeks of age, then take only three weeks to start producing the next generation. Each hen can produce up to 150 progeny within a year of its own hatching).

A further improvement in growth is due to improved nutrition. For current meat chicken breeds, the precise profile of nutrients such as energy, protein, essential amino acids, vitamins and minerals that the chicken needs at each stage of its growth has been studied precisely. For each feed ingredient, the levels of these nutrients digestible by the chicken has also been established. With this information, feeds can be formulated to match the chicken’s precise nutritional requirements throughout its lifecyle, thereby optimising growth.

Other gains made in meat chicken growth and performance are due to better husbandry techniques and health management.


Feed is made up of 85-90% grains, such as wheat, sorghum, barley, oats, lupins, soybean meal, canola and other oilseed meals and grain legumes.  For this reason, international grain prices affect the cost of production very significantly.  To read more about the significant proportion of wheat and grain more generally that is being purchased by the Australian chicken meat industry, click here.  You will learn that 5% of grains grown in Australia are purchased by our industry.

Hormones are not added to chicken feed or administered to commercial meat chickens or breeders in Australia. Hormone supplementation is a practice that has been banned internationally for forty years. The ban is supported by the Australian Chicken Meat Federation (see ACMF hormone policy).

Meat chicken diets are formulated to strict nutritional standards. A rough guide to the specifications of some of the key nutrients needed by a growing meat chicken is:

Nutrient Specification of a Broiler Diet (Grower)  
Energy 13 MJ/kg
Crude Protein 20.5%
Lysine (digestible) 1.1%
Total sulphur amino acids (digestible) 0.7%
Calcium 0.9%
Phosphorous (available) 0.4%
Sodium 0.2%
Chloride 0.2%

The optimum and most economical combination of feed ingredients that meets the strict nutritional specifications at any particular time is selected by ‘least cost formulation’ computer programs.  The dietary formulation will therefore vary with changes in the availability, price and quality of specific feed ingredients, the location and season and the age of any particular broiler flock. For example, diets fed to meat chickens in the south eastern states will predominantly be based on wheat, whereas sorghum provides a greater contribution to the diet of meat chickens in Queensland and lupins will normally only enter the diets in WA and SA.

Generally speaking, cereal grains provide the energy component of the diet, and soyabean meal, canola meal and meat and bone meal primarily provide the protein. In some areas, grain legumes such as lupins are used as a component of broiler diets where they have the dual role of supplying energy and protein. Vegetable oils or animal fats (such as tallow) might be included in the diet to provide additional energy.

Meat chickens have very specific requirements for particular amino acids, which are the ‘building blocks’ of proteins. The amino acids lysine and methionine are also added to diets because they are generally not present in sufficient amounts in the grains and protein sources to meet the nutritional needs of the birds. Meat chicken diets are also fortified with additional vitamins and minerals and, where necessary, other essential amino acids to ensure that the broilers’ very precise requirements for these nutrients are met.

A ‘typical’ broiler feed might look something like the following.

Composition of a Typical Broiler Feed






Soyabean Meal


Canola Meal


Meat & Bone Meal








Vitamins & Trace Minerals




As the chicks grow, the composition and form of the feed is changed to match their changing nutritional needs and increasing mouth size. The ‘starter’ feed, which is in small crumbles just big enough for baby chicks to eat, is replaced with ‘grower’ feed as soon as they are large enough to eat fully formed pellets. After about 25 days, the chickens move on to a ‘finisher’ feed, and then often to a ‘withdrawal’ feed just before harvest.

Almost all broiler feed used in Australia these days is steam pelleted (in crumble form, in the case of baby chick feeds). Ingredients are ground, mixed together, steam conditioned and compressed into beak sized, well-formed pellets. The high temperatures applied in pelleting kill many bacteria that may be in the feed ingredients, essentially sterilising the feed. Some companies include whole grain mixed with pellets.

Feed is delivered in bulk to growing farms by modern trucks incorporating pressurised blower units, ranging in capacity from 20 to 35 tonnes. The feed is stored in silos on site and dispensed mechanically to chickens in the sheds.

A flow diagram of the processes involved in the manufacture of chicken feed in a typical, large Australian feed mill is below.

Main farming and processing methods: what are the main differences

The description offered above represents what we generally call the conventional farming method. Chickens are raised in large enclosed barns with litter (wood shavings, rice hull etc) on the floor.  The older style farms have some "soft"side walls (called curtains)  which allow a degree of control over air movement and temperature within the shed. Modern sheds are generally of the tunnel ventilated type, with solid walls, large fans placed at one end of the shed and air inlets at the other end which draw the air across large pads that can be soaked with water to generate evaporative cooling of the air.  Floors are either concrete or compressed clay soil to allow thorough cleaning between batches of chickens (all chickens are removed from a shed and the shed is cleaned and disinfected before the next batch of one day old chicks is delivered).  The break of several days between the fully grown birds being picked up and the new batch of day olds being placed is an important aspect in our effort to maintain the chickens free of disease and contamination.

Conventionally produced chicken represents about 90% of the total production in Australia.  Free-range chicken makes up the remainder, with certified organic being a free-range system with some additional features.

Free range and organic chicken production

Free range chicken meat accounts for 10 to 15% of chicken produced, with less than 1% of the total production also being organic.

Free range meat chickens are produced using similar management, housing and feeding practices as conventional meat chickens. The major differences are that free range chickens are allowed access to an outside run for part of each day (at least post the brooding period) and often have lower target stocking densities. Depending on the accreditation program adhered to, use of antibiotics to treat sick birds may preclude the meat from these birds being sold as free range.

The main certifier of free range chicken meat in Australia is Free Range Egg and Poultry Australia Ltd (FREPA). The standards that free range meat chickens must comply with to be certified by FREPA can be viewed at is also an "outdoor systems" RSPCA Accredited Farming Scheme Standard; details are available on the RSPCA website.

Certified organic meat chickens have two additional requirements:

  • Feed must be predominantly from certified organic ingredients.
  • Birds cannot be treated with routine vaccination. There are exceptions, such as where treatment is required by law or disease cannot be controlled with organic management practices.

Certified organic chicken meat bears a certification logo from an approved organisation.  Please seek more detailed information from the relevant accreditation body.

Note that at present chicken meat can be described as ‘organic’ without being certified by an organic association. Therefore it is important to look for a relevant certification and to seek detailed information on the actual requirements mandated by the relevant standard from the organisation administrating the standard.

Comparison Table of the Main Commercial Meat Chicken Farming Systems


If chicken meat is sold as:


Free Range or Outdoor Systems

Certified Organic

Kept in cages




Housed in large barns




Access to outdoor forage areas

during daytime 


Yes. Required once chicks are adequately feathered

Yes. Required once chicks are adequately feathered

Stocking Density Maximum (inside the barns)

28-40kg/m2 depending on the standard of the ventilation provided in barns

16-34kg/m2 depending on the standard of the ventilation provided in barns


Age of birds at harvest

35 – 55 days

35 – 55 days

65 – 80 days

Given growth hormones




May be given antibiotics for prophylactic and/or therapeutic purposes


Depends on accreditation program (under some standards, if antibiotics are required,  meat may no longer be sold as free range)

No (if antibiotics are required, can no longer be sold as organic)

Feed consists mainly of grains




Feed may contain supplements such as vitamins and amino acids




Feed has to come from organic production (no chemical fertilizers, pesticides and herbicides used)




Use of GM products in feed

Yes, to a limited extent (soy meal is not available in sufficient quantities from local sources and imported soy meal may contain GM grain)

Yes, to a limited extent (soy meal is not available in sufficient quantities from local sources and imported soy meal may contain GM grain)


Model Code of Practice for the Welfare of Animals applies




Controls in place to ensure adherence to these standards

Most chickens are grown under contract to processors and the farms are supervised by the processor’s farming manager and vet

Monitored by organisations that accredit farms such as FREPA and RSPCA; comment under “Conventional” also applies here

Accreditation provided by organization approved by the Australian Quarantine Inspection Service; independently audited

Note: Chicken marketed as "chemical free" comes from  birds raised in a conventional manner.  The difference is in the processing plant where no chlorine is used, In most processing plants in Australia, chicken carcases are placed in a water and ice mixture to wash the carcasses and to cool them to below 5 degrees Celsius.  This water is generally sanatized by the addition of chlorine at levels of 3-5 ppm to control microbial contamination such as Salmonella and Campylobacter that occur naturally on meat.


Corn fed and grain fed chicken is produced as the name indicates by feeding chickens a substantial diet of corn resp. grain.  All chickens are fed grains as a major part of their diet. In Australia, the grain is mainly wheat and sorghum. The grains used will depend on the local availability so that in the US, for example, corn is the staple ingredient rather than wheat.  Corn-fed chicken tends to have a slightly yellow appearance.

The chemical-free label refers to a difference in the processing, not the farming. As explained in the footnote to the table above, it indicates that no chlorinated water has been used in the processing plant, with water being sanitized by exposure to UV light rather than addition of chlorine, and carcasses being cooled by exposure to a cold air stream rather than an iced water bath.

Finally, the claims "no added hormones" and "no cages" APPLY TO ALL CHICKEN MEAT SOLD IN AUSTRALIA regardless of the farming system.  The claim "produced in Australia" is applicable to almost all chicken meat sold in Australia.  Small quantities of cooked chicken meat is being imported from New Zealand and retorted (e.g. canned) products containing chicken may also be imported.

Keeping Flocks Healthy

Increasingly, the emphasis in flock health program is on prevention rather than treatment.

Vaccination, farm hygiene and biosecurity are the most important strategies to keep flocks healthy. For poultry diseases caused by viruses, they are the only useful strategies.

For some diseases these approaches are insufficient, unavailable or uneconomical (see Coccidiosis and Necrotic Enteritis later) and other methods of control are necessary at this point in time.

In unusual circumstances where a bacterial disease has flared and all other management strategies have failed, the veterinarian will treat the birds with animal-friendly antibiotics (see Therapeutic Use of Antibiotics).


Breeder flocks will be vaccinated against a range of diseases during their lifetime. The actual diseases vaccinated against, vaccines used and program and timing of vaccinations will vary for each company.

Great Grandparents, the most valuable birds, are usually vaccinated for infectious bronchitis, Marek’s disease, infectious laryngotracheitis, infectious bursal disease, chicken anaemia virus, inclusion body hepatitis, Newcastle disease and fowl pox; and may also be vaccinated against egg drop syndrome; Mycoplasma gallisepticum, Mycoplasma synoviae and coccidiosis.

Grandparent and Parent breeder flocks will be vaccinated against a similar range of diseases, and some may be vaccinated for fowl cholera and Salmonella as well. Breeder flocks are vaccinated, not only to protect their own health and productivity, but in many cases to provide protection for their progeny chicks through the antibodies passed on in the yolk sac. This is particularly important in the case of infectious bursal disease, for which protection of broiler flocks is largely dependent on maternal antibodies.

Blood tests are used to monitor the effectiveness of vaccination. Some companies have their own laboratories, while others use university, government or private diagnostic laboratories.

Chicks are generally vaccinated for infectious bronchitis and Marek’s disease. As Newcastle disease vaccination is compulsory for all commercial poultry flocks, broiler chicks are vaccinated at the hatchery or in the field through drinking water at 7 -14 days of age.

Hygiene and Biosecurity

Farm hygiene and biosecurity practices are implemented at both breeder and broiler farms to reduce the risk of disease moving on to farms from outside sources such as wild birds or other farms, moving between sheds on the same farm, being carried over between batches in a shed, or being passed from parents via the egg.

These are discussed in more detail at Farm Biosecurity and Hygiene under Breeder Farms and at Cleanout and Farm Biosecurity under Broiler Farm. Farmers adhere to the procedures documented in the “National Biosecurity Manual for Contract Meat Chicken Farming”, which is available from the ACMF website.

Good hygiene in the hatchery helps to reduce the chances of infections being picked up by chicks while they are in the hatchery.

Measures are also taken at the feed mill to reduce the risk of any disease agents and other pathogens, particularly Salmonella, from getting into chicken feed from feed ingredients or from contamination of the finished feed.


Coccidiosis is a significant and common disease of all poultry all over the world. It is caused by a parasite which infects the gut of the chicken causing diarrhoea and significant production losses and mortalities.
It is treated by the use of coccidiostats. As coccidiosis is extremely common in all poultry raised on the ground, coccidiostats are routinely included in chicken feed.

Necrotic Enteritis

Necrotic enteritis is caused by the overgrowth of a bacteria called Clostridium perfringens in the gut and, when triggered, a high proportion of the flock can die. This condition is controlled by a combination of dietary management and the prophylactic and targeted use of one of four possible antibiotics, delivered in the feed.

For more information on the use of such products see Antibiotics under Consumer Issues.

Therapeutic Use of Antibiotics

Antibiotic use is important in chicken meat production to ensure the overall health and well being of chickens. Only antibiotics approved by Australia’s regulatory authorities and administered in accordance with strict regulatory guidelines are used. The Australian Chicken Meat Federation recommends the use of antibiotics in farm animals in two important ways:

  • therapeutic agents (used to treat the symptoms of a bacterial infection)
  • prophylactic (preventative) agents (used to prevent disease occurring in healthy animals).

Antibiotics are usually delivered via drinking water, not in feed. Only a veterinarian can authorise and supervise these treatments.

The antibiotic policy of the Australian Chicken Meat Federation states that:

  • Antibiotics must not be used to promote growth in chickens
  • Antibiotics are only to be used for therapeutic or preventative treatments against serious diseases such as necrotic enteritis.
  • Antibiotics that are considered important for human use are not to be used in preventative treatments of chickens.
  • Antibiotics must be used under veterinary supervision and according to good veterinary practice.
  • At all times withholding periods set by regulatory authorities must be observed.
  • The industry supports the Australian Government’s National Residue Survey, which conducts regular independent checks of residues of antibiotics in chicken meat and consistently shows that Australian chicken meat does not contain residues of antibiotics.

For more information on the use of such products see Antibiotics under Consumer Issues.

Metabolic diseases

Some conditions are not infectious but can affect the health of meat chickens and result in losses. These can be caused by intoxications, such as through the consumption of small quantities of fungal toxins brought into the feed through grains, or be metabolic in origin.

Intoxications are managed by the industry through the careful screening and sometimes treatment of raw ingredients and through careful feed formulation practices.

Fortunately, the incidence of metabolic conditions, such as skeletal deformities and heart attacks, has declined to very low levels in recent years, largely due to genetic selection for reduced susceptibility.

Furthermore, research into the environmental and nutritional factors that predispose to these conditions has led to the development and adoption of enlightened nutritional and husbandry practices designed to prevent the emergence of such conditions.

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