Origin of Domestic Chickens
It is believed that all domestic chickens descend from the Red Jungle Fowl (Gallus gallus), which was first domesticated at least five thousand years ago in Asia.
However, today’s meat chicken looks quite different from its wild ancestor – and quite different from modern laying chickens, which are bred specifically for egg production.
Breeding the Day-Old Meat Chicken
How the chickens that are used to produce meat in Australia are bred and how so many of them can be produced is summarised in the diagram below.
Most commercial meat chickens that are raised for human consumption worldwide today originate from ‘nucleus’ breeding flocks that are bred by a small number of international poultry breeding companies.
Developing new poultry genetics these days is a highly specialised and resource-intensive business. While up until the late 1990s, Australian meat chicken producers used chicken strains that were bred here in Australia, around that time the industry came to accept that local breeders just were not able to keep pace with the genetic progress being made by overseas dedicated poultry genetics companies. New genetics began to be imported from these international breeding companies based in the US and Europe.
Imported breeding stock gives Australia’s chicken meat industry access to the world’s best poultry strains.
Specialist breeding companies are continuously improving their breeding lines to select for a large range of positive and healthy traits. While meat yield and the efficiency with which birds convert feed to meat are important factors, so are traits such as reproductive fitness and fertility and resistance to disease and metabolic conditions. This is why the industry is continually importing new genetic strains, rather than just using existing meat chickens to breed more of the same.
The breeding effort is focused and involves a large number of animals. Breeding programs for meat chickens are undertaken by two large international poultry genetic companies – Aviagen and Cobb.
Almost all of Australia’s meat chickens today are derived from hybrid strains developed by Aviagen and Cobb, and the specific hybrid breeds used in Australia (referred to as ‘Ross’ and ‘Cobb’) are pretty much the same as are used right around the world. These strains have been developed, not by genetic engineering technology, but by good old conventional selective breeding techniques.
Selective Breeding: Selecting the Best to Produce the Next Generation
Selective breeding is the foundation of agriculture as we know it today. All agricultural endeavours fundamentally revolve around selective breeding. Dairy cows produce more milk, wheat crops are more abundant, corn cobs are juicier, sugar cane has a greater sugar content, sheep grow finer and more wool etc, all due, to some extent, to selective breeding. Without selective breeding, crops and livestock would be much more disease prone and far less productive. The basic concept of selective breeding is quite simple. It consists of selecting those plants or animals which show the desirable characteristics as the parents for the next generation in the breeding program, and doing so repeatedly over many generations.
A good illustration of what selective breeding can achieve is the substantial difference between today’s meat chicken and a chicken bred for table eggs (a so-called layer hen).
Selective breeding is particularly effective in situations where the reproductive cycle is short. That is particularly true of chickens. Breeding chickens reach sexual maturity and start producing eggs at about 20-25 weeks of age. It then takes only three weeks for those eggs to hatch and produce the next generation. If you start with a female chick, for example a meat Great Grandparent hen, she will produce at least 64 chicks in a year, 32 of which will be female. These 32 (Grandparent) hens will each produce at least 80 chicks, 40 of which will be female (Parent hens), and each of these will go on themselves to produce 140 meat chickens. In this way, one Great Grandparent hen will be responsible for passing on her genetics to at least 182,000 meat chickens, within a period of just 2.5 years.
Compare this with the situation in cattle. If a cow has a calf, that calf, if female, can only have her own calf in 2 to 3 years. In the same time that it takes to produce one single new generation of cattle, a single female chicken will have been responsible for 182,000 progeny. Hence the combination of short life span and massive reproductive capacity means that genetic selection can be very intense and very rapid.
It is easy to see why selective breeding has been so successful in the meat chicken industry.
Nevertheless, it is important to acknowledge that many other factors such as nutrition, animal and plant health, animal husbandry and farming techniques also contribute substantially to successful and sustainable farming.
Change in Focus Over the Past 50 Years
The focus of meat chicken breeding has evolved quite dramatically over time. While the basic science remains unchanged, the approach to selective breeding has generally become more sophisticated. In the 1960s, the goal of selective breeding in meat chickens was, in essence, increased growth rate and increased meat production (i.e. producing larger chickens in less time).
That approach has given way to a much more balanced effort by today’s breeding companies. This is illustrated in the diagram below, where 1960 goals are compared with those of today. It shows that the focus has changed from growth and yield to a broad spectrum of outcomes, with a clear emphasis on improving animal welfare, reproduction and fitness outcomes.
Modern breeding efforts aim for a well rounded breed that exhibits a range of important characteristics, with good growth being but one of a very broad spectrum of traits prized and selected for.
This change in the focus of breeding programs has translated into real improvements in the health, fitness and robustness of today’s modern meat chicken breeds. For some examples of how breeding programs conducted over the past 30/40 years have improved some key welfare indicators of modern strains of meat chickens, see here.
Importing Chicken Genetics & Quarantine
New chicken genetics are imported as fertile hatching eggs – these will hatch to become the Great Grandparents of the meat chickens reared for their meat.
These fertile hatching eggs have come from flocks which are monitored and rigorously tested before and after egg collection to ensure they are disease free. The eggs are sanitised on the outside and airfreighted to Australia in sealed containers. They are then transported directly to a quarantine facility – either a privately owned facility, or a government owned quarantine facility.
These quarantine arrangements aim to ensure exotic diseases do not enter Australia. Requiring new poultry genetics to be imported only as fertile eggs, not as live birds, helps to reduce this risk.
Quarantine facilities for hatching imported fertile eggs are highly biosecure premises designed to stop infection from escaping. For example, the air leaving the facility is filtered and strict protocols are followed to ensure that, should any disease agents be inadvertently imported in or on the fertile eggs, they cannot leave the facility on people, clothing, footwear, vehicles or equipment.
Quarantine facilities are situated away from other poultry facilities to protect quarantined birds from common poultry diseases. Each new importation into a quarantine facility will usually include three or four separate genetic lines – two female lines, with superior egg producing characteristics to ensure enough progeny can be produced, and one or two male lines, with superior traits to allow their progeny to grow and convert feed at optimal rates.
Imported eggs are incubated and hatched out in the quarantine facility where the chicks hatched from them are kept until they are nine weeks of age. Throughout their time in the quarantine facility, they are monitored and tested to confirm that they are free from a range of diseases common to poultry outside Australia, to ensure that they are safe to be released into the general poultry population.
Great Grandparent Flocks
The chickens released from quarantine facilities at nine weeks of age are to become the Great Grandparents of the chickens that are processed into the meat that you purchase at your local shop or butcher.
These are extremely valuable birds, due to the investment required to get them to Australia and their highly prized genetic potential.
When they come out of the quarantine facility, Great Grandparent chickens are housed in isolated farms located strategically around Australia.
Great Grandparent hens start producing eggs from about 22 – 24 weeks of age and produce around 100 fertile eggs in their 52-week lifetime. The fertile eggs they lay are hatched out in hatcheries to produce the next generation – the Grandparents of commercial meat chickens.
Grandparent flocks are reared and go on to produce fertile eggs on breeder farms similar to those used to house Great Grandparent flocks. There is some crossing of breeding lines in this generation to produce two distinct male and female lines in their progeny.
Grandparent flocks start producing eggs at about 22-24 weeks of age and in their lifetime (to about 60 weeks of age) produce between 100 – 120 fertile eggs. These fertile eggs from Grandparent flocks are collected and hatched out to produce the next generation of birds, called the Parent breeders.
Parent breeders are hatched from the fertile eggs from Grandparent flocks and, after arrival from the hatchery at one day-old, are reared, housed and managed much like the Great Grandparent and Grandparent flocks. Distinct male and female lines of Parents are crossed to produce the next generation.
Parent birds are kept until approximately 64 weeks, and produce about 160 fertile eggs. It is this generation of breeders that produces the fertile eggs that are hatched to produce the meat chicken flocks whose meat is processed for human consumption (the commercial meat chicken). That’s why they are referred to as the “Parent” breeders.
Surplus male breeders, and birds of breeding lines not needed for the next generation (referred to as ‘off-sexes’), are either culled upon hatching or grown out for meat.
Breeder flocks are kept on the floor in barns. The floor of the barn is usually covered with a bedding material, such as wood shavings or rice hulls, although some are housed on wooden slatted floors.
All generations of Australian meat chickens and meat breeders are raised in barns, not cages.
Breeder Flock Management During Rearing and Laying
On arrival at the breeder farm from the hatchery, day-old breeder chicks are placed on the floor of a climate controlled, well ventilated rearing barn with ready access to feed and water and feeding points. Breeder chickens are not fed or in any way administered hormones.
As breeder flocks approach sexual maturity (usually between 18-20 weeks of age), they are transferred to laying barns, which are similar to rearing barns but include banks of nest boxes for them to lay in. There is usually one nest for every five hens in the shed.
There is usually one male to every ten breeder hens placed in a laying barn.
Breeding farms follow management programs recommended by the overseas breeding company. Each new strain of chicken imported has subtly different requirements, and fine-tuning requires a great deal of skill and experience. This includes managing bird health, maintaining the correct composition and quantity of feed, and ensuring proper lighting, with the aims of ensuring that:
- flocks remain healthy and productive
- flocks come into production at the right time
- breeder hens produce the optimal number of eggs over their laying cycle
- flocks produce fertile, high quality, hatchable eggs.
The eggs from these flocks are collected and sent to a hatchery.
Feeding Breeder Flocks
Body weight and flock health is regularly monitored and reviewed. Breeder flock feed is usually restricted during rearing and laying to ensure the birds grow uniformly, as egg production can be affected by excess body fat. The composition of the feed for breeder flocks in lay differs from that given to commercial meat chickens (see Feed) in several key respects:
- Breeder feed is lower in protein to satisfy the requirements for egg production vs growth
- Breeder feed is lower in energy content, to help slow growth rate/body weight
- Breeder feed is much higher in calcium to meet the hen’s needs for egg shell formation
- Breeder feed contains higher levels of key vitamins and trace minerals, which impact on the hatchability of their eggs.
Breeder chickens are not fed or in any way administered hormones in Australia.
Managing Biosecurity, Flock Health and Hygiene on Breeder Farms
Breeder flocks are vaccinated against a range of diseases. This protects their own health and productivity and gives added protection to chicks through antibodies passed on in the yolk sac of the eggs they lay.
One of the key elements of successful breeder farm management is maintaining good farm biosecurity. Biosecurity procedures aim to keep birds healthy by reducing the chance of disease getting onto the farm, spreading between barns, or being passed between batches within the same barn.
Biosecurity measures employed on meat breeder farms include:
- shower-on, shower-off (including washing hair) for all personnel and visitors
- a complete change of clothes in the shower facility
- strict control of visitor movements
- wild animal-proof security fencing
- locked security gates
- bird, vermin and animal proof sheds
- treated water supply
- full cleanout and decontamination of barns between batches
- restrictions placed on entry of feed and other vehicles to the property
- full sanitation and fumigation of any equipment entering the farm
- no staff or visitors to the farm to have had any contact with other poultry for 72 hours
- footwear changed between barns
- hands washed or gloves changed between barns.
When a breeder flock is removed from a barn, the barn and all equipment in it is rigorously cleaned and disinfected. The barn is then left empty for a couple of weeks before a new flock is placed in it to ensure that it is clean and ready for the next flock.
Fertile hatching eggs from breeder farms are sent to a hatchery to be incubated.
On arrival at the hatchery, they are placed in racks in shelves, fumigated to kill any bacteria or viruses on the egg shell (if they haven’t already been fumigated at the farm) and held in a cooled storage room until ready to commence incubation. Incubation doesn’t need to commence immediately, and fertile eggs can be held in storage, usually for no more than a week, before entering the incubation process. This allows hatching to be planned to meet the company’s future day-old chick needs.
The incubation process lasts a total of 21 days and involves two stages. These are called the setter stage and the hatcher stage.
Hatchability is the percentage of live chicks that are successfully hatched from a set number of fertile eggs entering the incubation process. This is affected by:
- The health, age, nutrition and fertility of the breeder flock – hatchability declines as flocks age
- The genetic line of breeder – eggs from Great Grandparent flocks might average up to 80% hatchability, rising to 85% hatchability for eggs from Parent flocks
- How well the incubation conditions provided have met the embryo’s needs – which comes down to how well the incubation process has been managed
- How well eggs have been handled since being laid
- The level of hygiene on the farm and in the hatchery – dirty eggs can be a source of bacteria which can kill the developing embryo and spread between eggs within the hatchery.
Good hatchery hygiene is important to ensure that the chicks do not pick up an infection in the hatchery and are healthy and vigorous on release.
After hatching, the chicks are graded and checked that they are fit enough to go out to the farm. They may be vaccinated for diseases such as infectious bronchitis, Newcastle disease and Marek’s disease. The chicks are then counted and dispatched to breeding or chicken rearing farms.
When a chick hatches it absorbs into its abdomen what remains of the yolk, giving it nutrients which last until it is delivered to a farm where it will be reared.
Growing Meat Chickens
This section covers all aspects of how meat chickens are reared, from the point that the chicks leave the hatchery and arrive at the farm, to when the chickens reach market weight.
Hatchery to Farm
Chicks are transported from the hatchery to meat chicken farms, usually in ventilated chick boxes in specially designed, air-conditioned trucks. Although the remains of the yolk sac that is absorbed into the chick’s abdomen at hatching contains sufficient nutrients and moisture to sustain the chick for at least 72 hours, it is important that chicks receive warmth, feed and water as soon as possible after hatching.
Meat Chicken Farm
Most commercial meat chicken farms are intensive, highly mechanised operations that occupy relatively small areas compared with other forms of farming.
Commercial meat chickens are grown on the floor of large poultry barns. The floor of the barn is covered in an absorbent bedding material, such as wood shaving or rice hulls, which is referred to as “litter”. MEAT CHICKENS ARE NOT KEPT IN CAGES – this applies to all of the production systems used in the Australian chicken industry. The main production systems are generally referred to as conventional (barn), free-range and organic. For a simple
comparison of these systems, click here.
A meat chicken farm will comprise several barns, each separated from the others by a distance of between 12-15 metres. There are usually at least two barns on a farm, and sometimes in excess of 12 barns, along with other farm infrastructure such as feed silos, utilities and reception shed, equipment sheds and very often the farm owner’s or manager’s house.
Meat chickens are reared in large poultry houses, usually referred to as ‘barns’, ‘sheds’ or ‘houses’. Barn sizes vary, but a typical new barn might be 150 metres long and 15 metres wide.
Up to 25 years ago, the majority of chicken barns in Australia were what is referred to as ‘naturally ventilated’, with the sides of the barn partially open but enclosed with wire netting. In these barns, the amount of air circulating through, and therefore the temperature, is changed by raising or lowering curtains running along the side of the barn, or by a vent opening at the top. Ceiling fans are used to encourage air flow, and water misting systems are used to cool birds by evaporative cooling in very hot conditions.
More recently, chicken farmers have moved to upgrade or replace their old housing with a more effective ventilation system called ‘tunnel ventilation’. Tunnel ventilated barns have fans at one end of the barn which pull air into the barn through cooling pads in the walls at the opposite end to the barn, over the chickens and out the fan end of the house.
This system is capable of moving vast volumes of air. A number of temperature sensors in the barn allow the fan settings to be adjusted as often as every three minutes, thereby rapidly responding to changes in the barn conditions. To work most efficiently, tunnel ventilated barns need to be designed and equipped in such a way that there are minimal barriers to air movement or leakages which might otherwise lead to air turbulence and reduce their effectiveness and efficiency.
Feed lines and pans run the length of the barn and are supplied automatically from enclosed silos outside the barn. Water lines run the length of the barn in several parallel lines, with drinkers at regular intervals.
Most barns have water delivered, not in troughs, but by equipment called ‘nipple drinkers’. The chicks are attracted to peck at the shiny stem of the drinking point, which makes the drinker release water directly into their mouth. Chicks learn very quickly that this is how they get water. For more information about how this works see: http://www.chicken.org.au/chookchat/whats-this/
Barns are also equipped with heating equipment, which allows the air in the barn to be heated to the high temperatures required by baby chicks. These heating systems are called ‘brooders’.
Preparing for the Arrival of Day Old Chicks
Prior to the scheduled arrival of a new batch of chickens on his/her farm, a farmer will do the following things:
- Clean the barn and all equipment, including feeding pans and drinking systems
- Spread a layer of bedding material (litter), such as sawdust, wood shavings or as rice hulls, across the entire barn floor
- Drop feeders and waterers to the correct height for baby chicks
- Check all feed and water systems to make sure they are functioning correctly and not leaking
- Preheat the barn to the correct temperature for baby chicks – a minimum of 32oC. It’s important that not just the air in the barn has been heated to the correct temperature – there must have been sufficient preheating time to allow the bedding material (often called ‘litter’) to be warmed up too
- Put down ‘chick paper’ underneath feeders, on which a small amount of feed is spread. This facilitates chicks finding food as quickly as possible after arrival
Arrival of Day Old Chicks at the Farm
On arrival at the farm, day old chicks are unloaded from the delivery truck in their chick trays or boxes and placed onto the floor of the barn.
They may initially be confined to a restricted area of the total barn (the ‘brooding area’), representing a quarter to a third of the entire floor area of the barn. This assists in providing supplementary heating from gas heaters or heat lamps. 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 and are typically grown together in the same barn.
As it is critical that a new flock gets a good ‘start’, young flocks of chicks are monitored and inspected regularly to make sure that they are comfortable and that they are observed to be feeding, drinking and behaving normally.
Rearing the Meat Chicken Flock
For the first two days of the flock’s life, the barn temperature is held at a minimum of 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 barn 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 barn temperatures within this range thereafter, although in barns oflarge birds, towards the end of rearing, the temperature may be reduced.
Shed temperature, humidity, air quality and moisture levels in the litter are managed by altering ventilation.
In older, naturally ventilated barns, this is achieved by the farmer manually raising or lowering the side curtains or activating stirring fans and misters.
In modern tunnel ventilated barns, ventilation systems are automatically controlled by a special type of computer in each barn (called a ‘shed controller’) so that changes can be made rapidly and regularly in response to the conditions in the barn. This aids the farmer but doesn’t replace him/her. For example, the farmer can override the controller if the behaviour of the chickens suggests that the conditions they are experiencing are not quite right. Some of the things that a farmer would be looking out for in this respect are described here: http://www.chicken.org.au/chookchat/meat-chicken-behaviour-how-do-farmers-use-it/.
The farmer or farm manager therefore has a pivotal role to play in making sure the conditions that the chickens are experiencing is optimal.
Generally, feed and fresh water is available to the chickens 24 hours a day, other than for days when chickens are to be collected for processing, in which case feed lines may be raised (winched up to the roof of the barn) some hours before the team is due to arrive to collect them, and drinkers are raised at the time that collection of birds is about to commence. For further information on what chickens are fed, see Feed.
The chickens have a defined day and night time in each 24 hour period. The lighting provided in fully enclosed barns, including tunnel ventilated barns, is generally brighter in the flock’s first week on the farm, when the farmer wants to give chicks the best possible opportunity to find feeders and drinkers, than it is for the rest of the rearing period. The lighting provided in the day time is usually dimmer than natural lighting to keep the flock calm and to minimise birds scratching and injuring each other, but is always sufficient for them to see by and to find feed and water. Dark periods are provided each day to allow the chickens time to rest.
Throughout the rearing period, the farmer checks his/her flocks regularly to monitor health and progress, to remove any dead birds, and to cull any severely sick or injured ones so that they do not suffer. Strict records are kept by the farmer of the chickens’ health, growth and behaviour, so that any emerging disease or other problem can be identified rapidly and acted upon. Over the life of the meat chicken flock, only about 4% of chickens are lost through natural causes or culling.
Farmers also check feeders and drinkers to make sure they are working correctly and not leaking.
Careful management of ventilation and drinkers keeps the litter (the bedding material) dry and clean. Poor litter affects air quality and can affect bird health and performance. If necessary, the farmer may also need to top up the litter, replace some of it, or aerate it mechanically, in order to maintain good litter quality.
Harvesting the Meat Chickens
In Australia, it is usual practice for a percentage of chickens to be harvested for processing on several occasions. This practice is referred to as ‘thinning out’ – sometimes as ‘partial depopulation’, or ‘multiple pick-up’ – and may be done up to five times, depending on the chicken company’s market requirements for different sized chickens. Thinning out barns allows more space for the remaining birds and helps with the management of optimal barn temperatures and air and litter quality.
The first harvest might occur as early as 30-35 days and the last at 55-65 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 protection from bruising during transport. In some cases, chickens are collected by a specially designed machine that uses a series of conveyor belts to move birds from the barn floor and deposits them into crates or modules. Irrespective of whether caught manually or mechanically, the crates or modules they are collected into are then handled by forklift equipment and loaded onto trucks for transport to the processing plant.
Cleaning Barns Between Flocks
When all the chickens have been removed from the barn, it is cleaned and prepared for the next flock of day old chickens.
The next flock generally arrives in one to two weeks, allowing down time in which the barn can be cleaned and prepared for the next flock. The break between consecutive flocks also reduces the risk of common ailments being passed between flocks as many pathogens die off.
Many farms undertake a full cleanout of the barn after every flock. This includes removing used bedding (referred to as litter), brushing floors, scrubbing feed pans, cleaning out water lines, scrubbing fan blades and other equipment, and checking rodent bait stations. The floor bases are usually rammed earth or cement and because low water volumes are used, there is little water runoff. On other farms, a partial clean up of the barn is done after each flock, which might include treating the old bedding by partial composting before respreading and/or topping up with fresh bedding material, and cleaning and sanitising equipment. In such cases a full cleanout is done after every second or third flock of chickens.
The barn is often disinfected after cleaning, using low volumes of disinfectant which is sprayed throughout. An insecticidal treatment may be applied in areas where insects such as beetles are a problem and could threaten the next flock. Disinfectants and insecticidal treatments must be approved by the Australian Pesticide and Veterinary Medicines Authority as safe and fit for use in chicken barns.
Number of Flocks a Year
As each meat chicken flock spends approximately 7 weeks in a barn and there is a 2 week break between flocks, farmers run about 5.5 flocks through a barn each year.
A number of factors affect the chickens’ growth rate and size at harvest. These include:
- 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 Meat Chickens Grow to Market Weight so Quickly?
Most of the improvement in growth rates over the past 60 years is due to the development and rapid adoption of improved breeds of chicken. This genetic gain has been achieved as a result of:
- 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. Breeder chickens reach sexual maturity and start producing eggs at about 20-25 weeks of age. It then takes only three weeks for those eggs to hatch and produce the next generation. Each hen can therefore produce up to 150 progeny within a year of its own hatching.
Improved nutrition has also contributed to the rate of growth of today’s meat chickens. 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 determined. 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 production cycle, thereby optimising growth.
Other gains made in meat chicken growth and performance are due to better husbandry (for example, better housing that optimises the environmental conditions for the chickens) and health management.
Feed is made up of 85-90% grains, legumes and oilseeds, including wheat, sorghum, barley, oats, lupins, soybean meal, canola and other oilseed meals and grain legumes. For this reason, droughts can affect the cost of production very significantly.
100% of the cereal grains (such as wheat and sorghum) and the legumes used are grown in Australia. The industry will utilise locally grown oilseed meals wherever possible, supplementing these with imported oilseeds to complement the nutritional requirements of the chicken.
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 more than fifty years. The ban is supported by the Australian Chicken Meat Federation.
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)||%|
|Total Sulphur Amino Acids (digestible)||0.9%|
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 chicken 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 be used in chicken 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 chicken 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 chickens. Meat chicken diets are also supplemented with additional vitamins and minerals and, where necessary, other essential amino acids to ensure that the chickens’ very precise requirements for these nutrients are met.
A ‘typical’ meat chicken feed might look something like the following:
|Composition of a Typical Broiler Feed||%|
|Meat and Bone Meal||5.0|
|Vitamins and Trace Minerals||0.5|
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 meat chicken 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. Most companies include whole grain mixed with pellets in the final ration, as it helps to stimutate a healthy gut.
Feed is delivered in bulk to chicken rearing farms by modern trucks incorporating pressurised blower units, ranging in capacity from 20 to 35 tonnes. The feed is stored in sealed silos on site and dispensed mechanically to chickens in the barns.
A flow diagram of the processes involved in the manufacture of chicken feed in a typical, large Australian feed mill is shown below.
Free Range, RSPCA, Organic – What are the Differences?
The industry often calls the system described above, where chickens are raised on the floor in large enclosed barns and do not have access to an outside area or range, as the ‘conventional’ production system.
While such barns are the fundamental housing unit provided in all Australian commercial meat chicken production systems, there are a range of variations to this and accreditation programs that farmers might belong to that affect the way that the farm might operate and how the chicken that comes from them might be labelled. These include free range, RSPCA-accredited and certified organic systems.
In free range production systems, in addition to their barn, the chickens are able to access an outdoors area (or ‘range’) during daylight hours after they are old enough to deal with the outside temperatures and big enough that they aren’t at high risk of predation. This happens from about 21 days of age onwards. Access to the outdoors area is provided through flaps or ‘popholes’ in the side of the barn.
Free range meat chickens are produced using similar management and feeding practices as for ‘conventional’ meat chickens. Apart from having access to an outdoors range for part of each day, they often have lower stocking densities inside the barn, to facilitate the chickens’ access to the barn openings and as it is also harder to control the inside environment of the barn if there are openings in the side. Depending on the accreditation program that a farmer belongs to, the 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 www.frepa.com.au. Chicken meat accredited under this program bears the logo shown above.
The RSPCA Approved Farming Scheme also has standards for outdoor systems, which some farms are accredited under. Details of the standards that apply are available on the RSPCA website.
The focus of organic agricultural systems is on avoiding the use of synthetic chemicals such as synthetic pesticides, herbicides, fertilisers and antibiotics.
In addition to having access to an outdoors area, like free range systems, certified organic production systems also meet the following additional requirements:
- Feed must be predominantly from certified organic ingredients
- Birds cannot be given antibiotics or routine vaccinations. There are exceptions, such as where treatment is required by law or disease cannot be controlled with organic management practices alone.
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 administrating organisation.
The RSPCA Approved Farming Scheme accredits chicken producers that meet the RSPCA’s animal welfare standards. These standards are species-specific and provide detailed requirements for the rearing, housing, handling, transport and slaughter of meat chickens. The RSPCA Approved standards reach beyond the current legal requirements while still being commercially viable.
There are numerous additional requirements that must be met under this scheme, but the main differences include a lower maximum stocking density than would be required in non-accredited chicken meat production, a requirement for perches and other enrichments (pecking objects) to be available, different lighting requirements, specific requirements for managing the bedding in chicken barns, and regular on-farm assessment by the RSPCA of accredited farms and other facilities to ensure compliance with the Scheme’s standards.
The RSPCA Approved standards for meat chickens accommodate farming systems that house animals in enriched indoor environments or in systems where they are housed in a large shed with outdoor access (free range). Producers that market their product as RSPCA Approved with outdoor access (free range) are required to meet the RSPCA’s indoor housing standards plus the outdoor standards.
How much of Australia’s chicken meat production comes from these systems?
- Between 65 – 70% of Australia’s meat chickens come from farms that are accredited under the RSPCA Approved Farming Scheme
- Between 18 – 20% of Australia’s chicken meat comes from farms that are accredited by Free Range Egg and Poultry Australia
- About 78% is accredited to one or both of the above schemes
- Less than 1% is certified organic
- The remainder (about 22%) is not accredited under any of these schemes.
Comparison Table of the Main Commercial Meat Chicken Farming Systems and Accreditation Schemes
|Farming System or Accreditation Scheme||Conventional (not FREPA, RSPCA or Organic accredited)||Free Range (FREPA accredited) or Outdoor Systems||Certified Organic||RSPCA Approved|
|Kept in cages||No||No||No||No|
|Housed in barns||Yes||Yes||Yes||Yes|
|Access to outdoor forage areas during daytime||No||Yes |
Required once chicks are adequately feathered
Required once chicks are adequately feathered
(unless specifically accredited to the Scheme’s Outdoor Access standards)
|Maximum Stocking Density (inside the barns)||28-40kg/m2 depending on the standard of the ventilation provided in barns||Depends on accreditation program: |
28-30kg/m2 depending on the standard of the ventilation provided in barns for FREPA accredited
28-34kg/m2 depending on the standard of the ventilation provided in barns for RSPCA Outdoor Access accredited
|25kg/m2||28-34kg/m2 depending on the standard of the ventilation provided in barns|
|Perches and/or other environmental enrichments required||No||No||Yes||Yes|
|Additional (beyond Model Code of Practice) standards for lighting duration and/or intensity apply||No||No||Yes||Yes|
|Beak trimming or toe trimming||No||No||No||No|
|Age of birds at harvest||35 – 65 days||35 – 65 days||65 – 80 days||35 – 65 days|
|May be given antibiotics for disease prevention, control or treatment||Yes||Depends on accreditation program (under FREPA standards, if antibiotics are required, meat may no longer be sold as free range)||No (if antibiotics are required, chicken meat can no longer be sold as organic)||Yes|
|Feed consists mainly of grains||Yes||Yes||Yes||Yes|
|Feed may contain supplements such as vitamins and amino acids||Yes||Yes||Yes||Yes|
|Feed has to come from organic production (no chemical fertilizers, pesticides and herbicides used)||No||No||Yes||No|
|Use of GM products in feed||Some GM feed ingredients may be used||Some GM feed ingredients may be used||No||Some GM feed ingredients may be used|
|Model Code of Practice for the Welfare of Animals – Domestic Poultry and Land Transport Standards apply||Yes||Yes||Yes||Yes|
|Controls in place to ensure adherence to these standards||Most chickens are grown under contract to chicken processing companies and the farms are supervised by the company’s farming manager and veterinarian||Audited or assessed by organisations that accredit farms such as FREPA and RSPCA; comment under “Conventional” also applies here||Accreditation provided by organic accreditation organisation; independently audited||Assessed by RSPCA assessors (staff)|
Some Other Labelling Terms Explained
Chemical free – A “chemical free” label refers to a difference in the way the chickens have been processed, not in the way they have been farmed. Chemical free chickens are raised in conventional barn housing systems and are fed the same feed as conventional chickens. The difference is at 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 carcases and to cool them to below 5oC. This water is generally sanitised by the addition of chlorine at levels of 3-5 ppm to control contamination with microbes such as Salmonella and Campylobacter. In “chemical free” processing, water is sanitised by exposure to UV light rather than by addition of chlorine, and carcases are cooled by exposure to a cold air stream rather than an iced water bath.
Grain fed – While some suppliers may label their chicken “grain fed”, the reality is that the term could apply to all chickens produced in Australia, as all chickens are fed grains as the major part of their diet. In Australia, the grains mostly used are wheat and sorghum, because these are the most widely available grains.
Corn fed – Corn fed chicken is produced, as the name suggests, by feeding chickens corn as part of their diet. All chickens are fed grains as the major component of their diet. In the case of corn fed chicken, corn is substituted for a proportion of the other grains that would normally comprise the diet (typically wheat and sorghum in Australia). The skin and fat of raw corn fed chicken tends to have a yellow appearance, which disappears upon cooking. The amount of the diet that needs to be corn to achieve this effect is approximately 20%.
No hormones and cage free – The claims “no added hormones” and “no cages” APPLY TO ALL CHICKEN MEAT SOLD IN AUSTRALIA, regardless of the farming system.
Produced in Australia – The claim “produced in Australia” is applicable to almost all chicken meat sold in Australia. Small quantities of raw and cooked chicken meat are imported from New Zealand and fully retorted (e.g. canned) products containing chicken may also be imported. For more information on the restrictions on importation of chicken and reasons for them, see here. For the ACMF’s position statement on importation, see here.
Processing Meat Chickens
Chickens are taken directly from the rearing farms to the processing plant where they are unloaded from their transport crates or modules, slaughtered, plucked, cleaned, cooled, graded and dressed or cut up and/or filleted. They are then either packaged and frozen or chilled, or processed further into various products prior to packaging and sale to distributors or direct to retailers and restaurants.
Processing plants are very large, highly mechanised operations. Much of the improvement in industry’s efficiency over the past five decades is due to increasingly automated poultry processing plants. Today, Australia’s largest poultry processing establishment kills and processes 104 million chickens per year, or 2 million chickens per week.
All poultry processing operations in Australia have systematic preventative approaches to managing food safety risks, with approved and regularly audited Hazard Analysis and Critical Control Points (HACCP) programs in place.