Broiler industry

The broiler industry is the process by which broiler chickens are reared and prepared for meat consumption. Worldwide, in 2005 production was 71,851,000 tonnes.
From 1985 to 2005, the broiler industry grew by 158%.
A key measure of performance is the feed conversion ratio, the ability to convert feed into edible product. In 2018 the FCR of broilers is about 1.5, or 1.5 kg of feed to produce 1 kg of meat. This compares very favorably with other sources of meat.
It is estimated that broilers produce 6 kg of greenhouse gas per 1 kg of meat, as compared to 60 kg GHG /kg for beef cattle.
In the 1980s, it was typical to produce a 2 kilogram chicken in 70 days. By 2018, this had reduced to just 29 days to produce a bird of the same weight.

Broiler industry structure

The broiler production process is very much an industrial one. There are several distinct components of the broiler supply chain.

Primary breeding sector

The "primary breeding sector" consists of companies that breed pedigree stock. Pedigree stock is kept on high level biosecure farms. Eggs are hatched in a special pedigree hatchery and their progeny then goes on to the great-grandparent and grandparent generations. These eggs would then go to a special GP hatchery to produce Parent Stock which passes to the production sector.
In 2006, out of an estimated world population of 18 billion poultry, about 3% are breeding stock. The US supplied about 1/4 of world GP stock.
Worldwide, the primary sector produced 417 million parent stock per year.
A single pedigree-level hen might have 25000 parent stock bird descendants, which in turn might produce 3 million broilers.
Numerous techniques are used to assess the pedigree stock. For example, birds might be examined with ultrasound or x-rays to study the shape of muscles and bones. The blood oxygen level is measured to determine cardiovascular health. The walking ability of pedigree candidates is observed and scored.
The need for high levels of Research and development spending prompted consolidation within the primary breeder industry. As of 2017, only two sizable breeding groups remained:

Aviagen
Cobb-Vantress

In the UK, 2 international firms supply about 90% of the parent stock.
Due to the high levels of variation in the chicken genome, the industry has not yet reached biological limits to improved performance.
The full chicken genome was published in Nature, in December 2004. Today, all primary breeding groups are investing heavily in genomics research. This research mostly focuses on understanding the function and effect of genes already present in the breeding population. Research into transgenics — removing genes or artificially moving genes from one individual or species to another — has fewer prospects of gaining favor among consumers.

Broiler breeder farms

Broiler breeder farms raise parent stock which produce fertilized eggs. A broiler hatching egg is never sold at stores and is not meant for human consumption. The males and females are separate genetic lines or breeds, so that each line can be selected for optimal traits for productivity in either females or males, rather than a single line in which a compromise is reached between female and male optima. The chicks they produce will therefore be crossbreeds or "crosses". Since the birds are bred mainly for efficient meat production, producing eggs can be a challenge. In Canada, the average producer houses 15,000 birds that begin laying hatching eggs at 26 weeks of age. Each female bird will lay about 150 hatching eggs for the next 34 to 36 weeks, until the birds reach around 60 weeks of age and are slaughtered for meat. This cycle is then repeated when another flock of 20 week-old birds is put into the barns to begin the process again. As a general rule, each farmer produces enough broiler hatching eggs to supply chicks for 8 chicken producers.
Generally, parent flocks are either owned by integrated broiler companies or hatcheries or are contracted to them on a long-term basis.
Broiler breeder growing is typically a two-stage process. Parent stock purchased from a primary breeder is delivered as day-old. Most are first placed with on specialist rearing houses or starter farms until approximately 18 weeks of age, when they will be moved to a laying farm. The starter farm has the specialized brooding equipment to raise the chicks.

Rearing house

A typical rearing house design for Alabama-like climate :

size, single storey.
11,000 bird capacity
Ceiling is insulated
Exterior curtain side walls.
A "minimum ventilation" system is required for the heating period to provide a certain amount of fresh air.
A separate "tunnel ventilation" system with evaporative pad cooling is desired for hot weather in the later stage of the bird's growth.
Air inlets may be automatically adjusted.
A negative ventilation system helps keep dirt and dust out of egg storage areas.
The entire house may be heated, or individual "brooders" may be used.
The floor is flat. There are no "slats" or "pits" for manure. There are no cages, and no nests. "Litter" covers the floor. When the chicks are introduced temporary barriers are used to keep them close to the heated areas.
"Black-out" design to keep out external light, so the day-night cycle can be controlled.
An automatic timer-controlled lighting system. Dimmers allow light intensity to be adjusted.
Automatic feeders to distribute feed. Typically this consists of an endless chain in a trough or with individual pans. A silo or bin outside provides storage.
Automatic drinkers provide water. There are several different designs, with "nipples" or "round" drinkers being popular.
Feeders and drinkers are height adjusted as the birds grow, and can be raised on chains or wires to allow cleanout of the barn.

Chicks require warm air temperatures, which is reduced as the birds mature:

Age	Brooder Temperature	Whole-House Heating Temperature
0 days
14 days

Chicks might be debeaked at 7–10 days age. During rearing, bird weight is carefully monitored, as an over-weight bird will be a poor egg producer. The feed mix will be adjusted to meet nutritional needs at each stage. Feed might be restricted to control body weight, for example with "skip a day" feeding, or feeding 5 days out of 7. A vaccination program is carried out, which ensures the longevity of the parent stock, and the immunity may be passed to the broiler progeny. Males and females, are usually raised separately.

Laying house

The birds are then moved to broiler breeder laying houses or production barns. The birds are typically placed into crates, and transported by truck to a separate facility. Males and females are raised together at this point. Outwardly the laying house will resemble the rearing house. Inside, about one-half of the floor might consist of raised 'slats.' During the production run, manure will drop through the slats and accumulate in the pit underneath the slats. The birds are not generally caged, especially since the roosters must mate with the hens to fertilize the eggs. Nests are provided for laying hens. Both automatic and manual nesting systems exist. Manual nests are usually stuffed with straw or shavings and eggs are hand-collected. Automatic systems usually have a plastic carpet lining, with a conveyor belt for egg collection. Careful layout and attention to bird behavior is required to avoid 'floor eggs'.
Depending on breed, egg production starts at 24–26 weeks of age. Production percentage climbs rapidly to a peak of 80–85% at 29–32 weeks, and then gradually declines with age. Hatchability tends to peak somewhat later than production at 34–36 weeks. Overall flock production will decline as mortality reduces the size of the flock and as the birds age out of their prime.
When the rooster mates with the hen, sperm enter the hen's oviduct and are stored within sperm storage glands. These glands can store more than half a million sperm, and sperm can remain viable for up to 3 weeks. However, a hen will have maximum fertility for only about 3 to 4 days after one mating. Therefore, the male-to-female ratio in a flock must be enough to ensure mating of every hen every 3 days or so. To maintain fertility, younger roosters may be introduced as the flock ages- a system known as 'spiking'.
Eggs are collected a minimum of twice a day, and usually more frequently. Cracked or dirty eggs are separated, as they are not suitable for hatching. Undersized, oversized or double-yolk eggs are also unsuitable. The eggs might be disinfected by fumigation, are packed in 'flats' or trays, placed in wheeled trolleys, and stored in a cool climate-controlled area. The egg packing room and storage rooms are kept segregated to reduce contamination. The trolleys are delivered by truck to a hatchery perhaps twice a week.
At the end of the production cycle, the birds are called "spent fowl". Disposal of spent fowl may be a problem as consumer demand for them is poor.

Hatcheries

take the fertilized eggs, incubate them, and produce day-old broiler chicks.
Incubation takes about 21 days, and is often a two-step process. Initial incubation is done in machines known as setters. A modern setter is the size of a large room, with a central corridor and racks on either side. Eggs are held relatively tightly in trays, which are stored in the racks. Inside the setter, temperature and humidity are closely maintained. Blowers or fans circulate air to ensure uniform temperature, and heating or cooling is applied as needed by automated controls. The racks pivot or tilt from side to side, usually on an hourly basis. As an example, one commercial machine can hold up to 124,416 eggs and measures about 4.7 metres wide by 7.2 metres deep. Setters often hold more than one hatch, on a staggered hatch-day basis, and operate continuously. The setter phase lasts about 18 days.
On or about day 18, the eggs are removed from the setters and transferred to hatchers. These machines are similar to setters, but have larger flat-bottom trays, so the eggs can rest on their sides, and newly hatched chicks can walk. Having a separate machine helps keep hatching debris out of the setter. The environmental conditions in the hatcher are optimized to help the chicks hatch. As a commercial example, a large hatcher has capacity for 15,840 eggs, and measures about 3.3 metres by 1.8 metres.
Some incubators are single-stage, and entire trolleys of eggs can be rolled in at one time. One advantage of single-stage machines is that they are thoroughly cleaned after each hatch, whereas a setter is rarely shutdown for cleaning. The single-stage environment can be adjusted for eggs from different producing flocks, and for each step of the hatch cycle. The setter environment is often a compromise as different egg batches are in the machine at one time.
On hatch day, the trays are removed from the hatchers, and then the chicks are removed from the trays. Chicks are inspected, with the sickly ones being disposed of. Chicks may be by vaccinated, sorted by sex, counted, and placed in chick boxes. Stacks of chick boxes are loaded into trucks for transport, and arrive at the broiler farm on the same day. Specialized climate-controlled trucks are typically used, depending on climate and transport distance.
Chick sexing is optionally done to improve uniformity – since males grow faster, the weights are more uniform if males and females are raised separately. The birds are bred so that males and females have unique feather patterns or color differences. Unlike egg-laying poultry, males are not culled.
Typical hatchability rate in Canada in 2011 was 82.2%.. A UK source estimates 90% hatchability.