Broilers
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Breed A breed is a specific group of breedable domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist seve ...
broiler is any
chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
(''Gallus gallus domesticus'') that is bred and raised specifically for
meat Meat is animal Tissue (biology), tissue, often muscle, that is eaten as food. Humans have hunted and farmed other animals for meat since prehistory. The Neolithic Revolution allowed the domestication of vertebrates, including chickens, sheep, ...
production. Most commercial broilers reach slaughter weight between four and six weeks of age, although slower growing breeds reach slaughter weight at approximately 14 weeks of age. Typical broilers have white feathers and yellowish skin. Broiler or sometimes broiler-fryer is also used sometimes to refer specifically to younger chickens under , as compared with the larger roasters. Due to extensive breeding selection for rapid early growth and the husbandry used to sustain this, broilers are susceptible to several welfare concerns, particularly skeletal malformation and dysfunction, skin and eye lesions and congestive heart conditions. Management of ventilation, housing, stocking density and in-house procedures must be evaluated regularly to support good welfare of the flock. The breeding stock (broiler-breeders) do grow to maturity but also have their own welfare concerns related to the frustration of a high feeding motivation and beak trimming. Broilers are usually grown as mixed-sex flocks in large sheds under intensive conditions.


Modern breeding

Before the development of modern commercial meat breeds, broilers were mostly young male chickens culled from farm flocks. Pedigree breeding began around 1916. Magazines for the poultry industry existed at this time. A crossbred variety of
chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
was produced from a male of a naturally double-breasted Cornish strain, and a female of a tall, large-boned strain of white Plymouth Rocks. This first attempt at a meat crossbreed was introduced in the 1930s and became dominant in the 1960s. The original crossbreed was plagued by problems of low fertility, slow growth and disease susceptibility. Modern broilers have become very different from the Cornish/Rock crossbreeds. As an example, Donald Shaver (originally a breeder of egg-production breeds) began gathering breeding stock for a broiler program in 1950. Besides the breeds normally favored,
Cornish Game Cornish game hen (also Rock Cornish game hen) is the USDA-approved name for a particular variety of broiler chicken, produced from a cross between the Cornish and White Plymouth Rock chicken breeds, that is served young and immature, weighing ...
,
Plymouth Rock Plymouth Rock is a boulder in Plymouth, Massachusetts, that symbolizes the historical disembarkation site of the '' Mayflower'' Pilgrims who founded Plymouth Colony in December 1620, and has been claimed to be the Pilgrims' actual landing site. ...
,
New Hampshire New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
, Langshans, Jersey Black Giant, and Brahmas were included. A white feathered female line was purchased from Cobb. A full-scale breeding program was commenced in 1958, with commercial shipments in Canada and the US in 1959 and in Europe in 1963. As a second example, color sexing broilers was proposed by Shaver in 1973. The genetics were based on the company's breeding plan for egg layers, which had been developed in the mid-1960s. A difficulty facing the breeders of the color-sexed broiler is that the chicken must be white-feathered by slaughter age. After 12 years, accurate color sexing without compromising economic traits was achieved.


Artificial insemination

Artificial insemination is a mechanism in which spermatozoa are deposited into the reproductive tract of a female. Artificial insemination provides a number of benefits relating to reproduction in the poultry industry. Broiler breeds have been selected specifically for growth, causing them to develop large pectoral muscles, which interfere with and reduce natural mating. The amount of sperm produced and deposited in the hen's reproductive tract may be limited because of this. Additionally, the males' overall sex drive may be significantly reduced due to growth selection. Artificial insemination has allowed many farmers to incorporate selected genes into their stock, increasing their genetic quality. Abdominal massage is the most common method used for semen collection. During this process, the rooster is restrained and the back region located towards the tail and behind the wings is caressed. This is done gently but quickly. Within a short period of time, the male should get an erection of the phallus. Once this occurs, the cloaca is squeezed and semen is collected from the external papilla of the vas deferens. During artificial insemination, semen is most frequently deposited intra-vaginally by means of a plastic syringe. In order for semen to be deposited here, the vaginal orifice is everted through the cloaca. This is simply done by applying pressure to the abdomen of the hen. The semen-containing instrument is placed 2–4 cm into the vaginal orifice. As the semen is deposited, the pressure applied to the hen's abdomen is released simultaneously. The person performing this procedure typically uses one hand to move and direct the tail feathers, while using the other hand to insert the instrument and semen into the vagina.


General biology

Modern commercial broilers, for example, Cornish crosses and Cornish-Rocks, are artificially selected and bred for large-scale, efficient meat production. They are noted for having very fast growth rates, a high
feed conversion ratio In animal husbandry, feed conversion ratio (FCR) or feed conversion rate is a ratio or rate measuring of the efficiency with which the bodies of livestock convert animal feed into the desired output. For dairy cows, for example, the output is milk ...
, and low levels of activity. Modern commercial broilers are bred to reach a slaughter-weight of about in only 5 to 7 weeks.Damerow, G. 1995. A Guide to Raising Chickens. Storey Books. As a consequence, the behaviour and physiology of broilers reared for meat are those of immature birds, rather than adults. Slow growing free-range and organic strains have been developed which reach slaughter-weight at 12 to 16 weeks of age. Typical broilers have white feathers and yellowish skin. Recent genetic analysis has revealed that the gene for yellow skin was incorporated into domestic birds through hybridization with the
grey junglefowl The gray junglefowl (''Gallus sonneratii''), also known as Sonnerat's junglefowl, is one of the wild ancestors of the domestic chicken together with the red junglefowl and other junglefowls. The species epithet commemorates the French explorer ...
(''G. sonneratii'').Eriksson, J., Larson G., Gunnarsson, U., Bed'hom, B., Tixier-Boichard, M., et al. (2008) ''Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken.'' PLoS Genet January 23, 200
Genetics.plosjournals.org
Modern crosses are also favorable for meat production because they lack the typical "hair" which many breeds have that must be removed by singeing after plucking the carcass. Both male and female broilers are reared for their meat.


Behavior

Broiler behavior is modified by the environment, and alters as the broilers' age and bodyweight rapidly increase. For example, the activity of broilers reared outdoors is initially greater than broilers reared indoors, but from six weeks of age, decreases to comparable levels in all groups. The same study shows that in the outdoors group, surprisingly little use is made of the extra space and facilities such as perches – it was proposed that the main reason for this was leg weakness as 80 per cent of the birds had a detectable
gait Gait is the pattern of Motion (physics), movement of the limb (anatomy), limbs of animals, including Gait (human), humans, during Animal locomotion, locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on s ...
abnormality at seven weeks of age. There is no evidence of reduced motivation to extend the behavioral repertoire, as, for example, ground pecking remained at significantly higher levels in the outdoor groups because this behavior could also be performed from a lying posture rather than standing. Examining the frequency of all sexual behaviour shows a large decrease with age, suggestive of a decline in
libido In psychology, libido (; ) is psychic drive or energy, usually conceived of as sexual in nature, but sometimes conceived of as including other forms of desire. The term ''libido'' was originally developed by Sigmund Freud, the pioneering origin ...
. The decline in libido is not enough to account for reduced
fertility Fertility in colloquial terms refers the ability to have offspring. In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to reproduce, which is termed fecundity. The fertility rate ...
in heavy cocks at 58 weeks and is probably a consequence of the large bulk or the conformation of the males at this age interfering in some way with the transfer of
semen Semen, also known as seminal fluid, is a bodily fluid that contains spermatozoon, spermatozoa which is secreted by the male gonads (sexual glands) and other sexual organs of male or hermaphrodite, hermaphroditic animals. In humans and placen ...
during copulations which otherwise look normal.


Feeding and feed conversion

Chickens are
omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...
s and modern broilers are given access to a special diet of high protein feed, usually delivered via an automated feeding system. This is combined with artificial lighting conditions to stimulate eating and growth and thus the desired body weight. In the U.S., the average
feed conversion ratio In animal husbandry, feed conversion ratio (FCR) or feed conversion rate is a ratio or rate measuring of the efficiency with which the bodies of livestock convert animal feed into the desired output. For dairy cows, for example, the output is milk ...
(FCR) of a broiler was 1.91 kilograms of feed per kilograms of liveweight in 2011, an improvement from 4.70 in 1925. Canada has a typical FCR of 1.72. New Zealand commercial broiler farms have recorded the world's best broiler chicken FCR at 1.38. The
microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...
of the broiler also has a large effect in addition to the birds nutrition and genetics on overall FCR.


Welfare issues

Artificial selection has led to a great increase in the speed with which broilers develop and reach slaughter-weight. Selection and husbandry for very fast growth means there is a genetically induced mismatch between the energy-supplying organs of the broiler and its energy-consuming organs. Rapid growth can lead to metabolic disorders such as sudden death syndrome and
ascites Ascites (; , meaning "bag" or "sac") is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdo ...
. Breeding for increased breast muscle affects the way chickens walk and puts additional stresses on their hips and legs. There is a high frequency of skeletal problems in broilers, mainly in the locomotory system. These leg abnormalities impair the locomotor abilities of the birds, and lame birds spend more time lying and sleeping. Increased inactivity is linked with an increase in
dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...
caused by a greater amount of time in contact with ammonia in
poultry litter In agriculture, poultry litter or broiler litter is a mixture of poultry excreta, spilled feed, feathers, and material used as bedding in poultry operations. This term is also used to refer to unused bedding materials. Poultry litter is used in ...
. Broilers are usually kept at high stocking densities. This can reduce feed intake and growth. Management conditions (litter quality, temperature and humidity) are however more important than stocking density. Many broilers die during the processes of catching, packing and transport.


World production and consumption

The commercial production of broiler chickens for meat consumption is a highly industrialized process. There are two major sectors: (1) rearing birds intended for consumption and (2) rearing parent stock for breeding the meat birds. A report in 2005 stated that around 5.9 billion broiler chickens for eating were produced yearly in the European Union. Mass production of chicken meat is a global industry and at that time, only two or three breeding companies supplied around 90% of the world's breeder-broilers. The total number of meat chickens produced in the world was nearly 47 billion in 2004; of these, approximately 19% were produced in the US, 15% in China, 13% in the EU25 and 11% in Brazil. Consumption of broilers is surpassing that of beef in industrialized countries, with demand rising in Asia. Worldwide, 86.6 million
tonnes The tonne ( or ; symbol: t) is a unit of mass equal to 1,000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...
of broiler meat were produced in 2014, and , the worldwide estimation of broiler chick population was approximately 23 billion.


Impacts of climate change


See also

*
Animal cruelty Cruelty to animals, also called animal abuse, animal neglect or animal cruelty, is the infliction of suffering or Injury, harm by humans upon animals, either by omission (neglect) or by commission. More narrowly, it can be the causing of harm ...
*
Animal welfare science Animal welfare science is the scientific study of the welfare of animals as pets, in zoos, laboratories, on farms and in the wild. Although animal welfare has been of great concern for many thousands of years in religion and culture, the investigat ...
*
Chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
*
Chicken tax The Chicken Tax is a 25 percent tariff on light trucks (and originally on potato starch, dextrin, and brandy) imposed in 1964 by the United States under President Lyndon B. Johnson in response to tariffs placed by France and West Germany on imp ...
* Cobb 500 * Concentrated animal feeding operation *
Early feeding In poultry farming, early feeding is the ad lib availability of feed and water for day-old chicks from the moment of hatching from the egg. Early feeding has a positive effect on chick performance because development and maturation of important or ...
*
Intensive animal farming Intensive animal farming, industrial livestock production, and macro-farms, also known as factory farming, is a type of intensive agriculture, specifically an approach to mass animal husbandry designed to maximize production while minimizing cos ...
*
Poultry farming Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion c ...
*'' The Chicken of Tomorrow'' * Ayam Kampong


References


External links

{{Authority control Chicken crossbreeds Poultry farming Articles containing video clips