View source for Broiler

{{Short description|Chicken bred for meat}}
{{About|the poultry|other uses}}
{{Use mdy dates|date = November 2019}}

{{Infobox poultry breed
| name          = Broiler
| image         = Poultry Classes Blog photo - Flickr - USDAgov.jpg
| image_size    =
| alt           =
| imagecaption  = A modern commercial broiler chicken
| status        =
| altname       =
| country       =
| distribution  = Worldwide
| standard      =
| use           = Meat, feathers
| nickname      =
| apa           =
| aba           =
| ee            =
| pcgb          =
| maleweight    =
| femaleweight  =
| skincolor     = Yellow, brown, black or mixed
| eggcolor      = white/light brown 
| comb          = red
| note          = 
| type          = [[Poultry]]
| latin         = 
}}

A '''broiler''' is any [[chicken]] (''Gallus gallus domesticus'') bred and raised specifically for [[meat]] production.<ref name="NASS US Broiler Industry Struct">{{cite web|last=Kruchten|first=Tom |title=U.S Broiler Industry Structure |publisher=National Agricultural Statistics Service (NASS), Agricultural Statistics Board, U.S. Department of Agriculture |date=November 27, 2002 |url=https://usda01.library.cornell.edu/usda/nass/industry-structure/specpo02.pdf |access-date=June 23, 2012 |archive-url=https://web.archive.org/web/20131229055826/http://usda01.library.cornell.edu/usda/nass/industry-structure/specpo02.pdf |archive-date=December 29, 2013 }}</ref> Most commercial broilers reach slaughter weight between four<ref name="Bessei">{{cite journal|vauthors=Bessei W |title=Welfare of broilers: A review |journal=World's Poultry Science Journal |volume=62 |issue=3 |year=2006 |pages=455–466 |s2cid=86638983 |doi=10.1017/s0043933906001085}}</ref> and six weeks of age, although slower growing breeds reach slaughter weight at approximately 14 weeks of age. Average broilers have white feathers and yellowish skin. Broiler or more uncommonly, '''broiler-fryer''' is also used sometimes to refer specifically to younger chickens under {{convert|4+1/2|lb|kg|order=flip}}, as compared with the larger roasters.<ref name="chicken types">{{cite web |url=https://www.thespruceeats.com/chicken-terminology-glossary-2313853 |title=What Are the Main Types of Chicken?|publisher=The Spruce Eats|date=January 7, 2019|access-date=June 16, 2020 |last=Gerrard|first=Gene}}</ref>

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.<ref name="93 years">{{cite web|url=http://www.cobb-vantress.com/publications/documents/PubArt_90years.pdf|title=How 90 years of poultry breeding has shaped today's industry|publisher=Poultry International|date=May 2007|access-date=July 1, 2012|last=Hardiman|first=J.|archive-url=https://web.archive.org/web/20120525190317/http://www.cobb-vantress.com/Publications/documents/PubArt_90years.pdf|archive-date=May 25, 2012}}</ref> Magazines for the poultry industry existed at this time.<ref name="93 years" /><ref>{{cite web|url=http://www.wattnet.com/ArticleDisplay.html?menuid=153&id=153|title=Watt Publishing History|publisher=Watt|access-date=July 1, 2012|archive-url=https://web.archive.org/web/20120719234630/http://www.wattnet.com/ArticleDisplay.html?menuid=153&id=153|archive-date=July 19, 2012}}</ref>  A [[Crossbreed|crossbred]] variety of [[chicken]] was produced from a male of a naturally double-breasted [[Indian Game (poultry)|Cornish]] strain, and a female of a tall, large-boned strain of white [[Plymouth Rock chicken|Plymouth Rocks]].<ref name=damerow /> 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]], [[Plymouth Rock chicken|Plymouth Rock]], [[New Hampshire chicken|New Hampshire]], [[Croad Langshan|Langshan]]s, [[Jersey Giant|Jersey Black Giant]], and [[Brahma chicken|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.<ref name="Hendrix Shaver">{{cite web|url=http://www.hendrix-genetics.com/en/about-us/history/institut-selection-animal-bv-isa/shaver/~/media/Files/ISA/History/History%20of%20Shaver%20Breeding%20Farms%20Ltd%20Canada.ashx|title=The History of Shaver Breeding Farms|publisher=Hendrix Genetics|year=2010|access-date=31 December 2013|last=Smith|first=Kingsley|archive-url=https://web.archive.org/web/20150924025651/http://www.hendrix-genetics.com/en/about-us/history/institut-selection-animal-bv-isa/shaver/~/media/Files/ISA/History/History%20of%20Shaver%20Breeding%20Farms%20Ltd%20Canada.ashx|archive-date=24 September 2015}}</ref> 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.<ref name="Hendrix Shaver" />

=== Artificial insemination ===
Artificial insemination is a mechanism in which spermatozoa are deposited into the reproductive tract of a female.<ref>{{Cite book |title=Pathways to Pregnancy and Parturition |last=Senger|first=Phillip|publisher=Current Conceptions Inc |year=2012 |location=Redmond}}</ref> 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.<ref name=":0">{{Cite journal |vauthors=Donoghue A, Wishart G |year=2000 |title=Storage of Poultry Semen |journal=Animal Reproduction Science |volume=62|issue=1–3|pages=213–232 |doi=10.1016/s0378-4320(00)00160-3|pmid=10924826 |url=https://zenodo.org/record/1260067}}</ref> 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.<ref>{{Cite journal|vauthors=Robinson FE, Wilson JL, Yu MW, Fasenko GM, Hardin RT |date=1993-05-01|title=The Relationship Between Body Weight and Reproductive Efficiency in Meat-Type Chickens |journal=Poultry Science |language=en|volume=72|issue=5 |pages=912–922 |doi=10.3382/ps.0720912|issn=0032-5791 |doi-access=free}}</ref> Artificial insemination has allowed many farmers to incorporate selected genes into their stock, increasing their genetic quality.<ref>{{cite journal|title=Artificial insemination: the state of the art |issue=2|pages=571–584|journal=Theriogenology|volume=59 |doi=10.1016/S0093-691X(02)01241-4|date=2003-01-15 |vauthors=Vishwanath R |pmid=12499005}}</ref>

Abdominal massage is the most common method used for semen collection.<ref name=":0" /> 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.<ref name=":1">{{Cite journal |vauthors=Blanco J, Wildt D, Höfle U, Voelker W, Donoghue A |year=2009 |title=Implementing artificial insemination as an effective tool for ex situ conservation of endangered avian species |journal=Theriogenology |volume=71|issue=1|pages=200–213|doi=10.1016/j.theriogenology.2008.09.019|pmid=19004491|hdl=10261/61328|hdl-access=free}}</ref>

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&nbsp;cm into the vaginal orifice. As the semen is deposited, the pressure applied to the hen's abdomen is released simultaneously.<ref name=":0" /> 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.<ref name=":1" />

== General biology ==
Modern commercial broilers, for example, Cornish crosses and Cornish-Rocks,{{Citation needed|date=January 2014}} 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]], and low levels of activity. Modern commercial broilers are bred to reach a slaughter-weight of about {{Convert|2|kg|abbr=on}} in only 5 to 7 weeks.<ref name=damerow>Damerow, G. 1995. A Guide to Raising Chickens. Storey Books. {{ISBN|0-88266-897-8}}</ref><ref name="USP&EA FAQ">{{cite web|url=http://www.uspoultry.org/faq/docs/industryFAQ.pdf|title=Poultry Industry Frequently Asked Questions Provided by the U.S. Poultry & Egg Association|publisher=U.S. Poultry & Egg Association|access-date=June 21, 2012}}</ref><ref name="CIWF" /> 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 [[Hybrid (biology)|hybridization]] with the [[grey junglefowl]] (''G.&nbsp;sonneratii'').<ref name="Erikson et al., (2008)">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, 2008 [http://genetics.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pgen.1000010.eor&ct=1 Genetics.plosjournals.org] {{Webarchive|url=https://archive.today/20120525080505/http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000010 |date=2012-05-25 }}</ref>  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.<ref name="Weeks et al., (1994)">{{cite journal|vauthors=Weeks CA, Nicol CJ, Sherwin CM, Kestin SC |year=1994 |title=Comparison of the behaviour of broiler chickens in indoor and free-range environments|journal=Animal Welfare |volume=3 |issue=3 |pages=179–192|doi=10.1017/S0962728600016833 |s2cid=82317011 }}</ref> 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]] 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]]. The decline in libido is not enough to account for reduced [[fertility]] 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]] during [[mating|copulations]] which otherwise look normal.<ref name="Duncan et al., (1990)">{{cite journal|vauthors=((Duncan IJH)), Hocking PM, Seawright E |year=1990|title=Sexual behaviour and fertility in broiler breeder domestic fowl |journal=Applied Animal Behaviour Science |volume=26|issue=3|pages=201–213 |doi=10.1016/0168-1591(90)90137-3}}</ref>

=== Feeding and feed conversion ===
Chickens are [[omnivore]]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]] (FCR) of a broiler was 1.91 kilograms of feed per kilograms of liveweight in 2011, an improvement from 4.70 in 1925.<ref name="NCC US Broiler Performance">{{cite web|url=http://www.nationalchickencouncil.org/about-the-industry/statistics/u-s-broiler-performance/|title=U.S. Broiler Performance|publisher=National Chicken Council|access-date=August 1, 2019}}</ref> Canada has a typical FCR of 1.72.<ref name="ON Canada Broiler Chicken FCR">{{cite web |url= http://canadiansmallflockers.blogspot.ca/2013/08/its-alive.html |title=Ontario Canada FCR|publisher=Small Flock Poultry Farmers of Canada|access-date=May 29, 2015|date=2013-08-21}}</ref> New Zealand commercial broiler farms have recorded the world's best broiler chicken FCR at 1.38.<ref name="NZ Broiler FCR Performance">{{cite web|url=http://www.wattagnet.com/154106.html|title=NZ FCR Broiler Performance|date=August 27, 2012 |publisher=Watt AgGate|access-date=May 29, 2015}}</ref> The [[Poultry Microbiome|microbiome]] of the broiler also has a large effect in addition to the birds nutrition and genetics on overall FCR.<ref>{{Cite web |title=Host genetics and gut microbiota contribute to feed efficiency in chickens |doi=10.21203/rs.3.rs-967786/v1 }}</ref>

== Welfare issues ==

{{main|Welfare of broiler chickens}}

[[File:Broiler chicks.jpg|upright|thumb|One-day-old chicks arriving to be unpacked and placed in shed]]

Artificial selection has led to a great increase in the pace of which broilers develop and reach slaughter-weight.<ref name="Bessei"/> 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.<ref name="CIWF" /> Rapid growth can lead to metabolic disorders such as sudden death syndrome and [[ascites]].<ref name="Bessei" /> Breeding for increased breast muscle affects the way chickens walk and puts additional stress on their hips and legs.<ref name="CIWF" /> There is a high frequency of skeletal problems in broilers, mainly in the locomotory system.<ref name="Bessei" /> These leg abnormalities impair the locomotor abilities of the birds, and lame birds spend more time lying and sleeping.<ref>{{cite journal |author1=Vestergaard, K.S. |author2=Sonatra, G.S. |year=1999|title=Relationships between leg disorders and changes in behaviour of broiler chickens |journal=Veterinary Record |volume=144|issue=8 |pages=205–209 |doi=10.1136/vr.144.8.205 |pmid=10097343 |s2cid=7739290}}</ref> Increased inactivity is linked with an increase in [[dermatitis]] caused by a greater amount of time in contact with ammonia in [[poultry litter]].<ref name="Bessei"/> Broilers are usually kept at high stocking densities.<ref name="CIWF" /> This can reduce feed intake and growth.<ref name="Bessei" /> Management conditions (litter quality, temperature and humidity) are however more important than stocking density.<ref>{{cite journal|vauthors=Dawkins MS, Donelly S, Jones TA |year=2004|title=Chicken welfare is influenced more by housing conditions than by stocking density |journal=Nature |volume=427|issue=6972|pages=342–344 |doi=10.1038/nature02226 |bibcode=2004Natur.427..342S |pmid=14737165|s2cid=4354183}}</ref> Many broilers die during the processes of catching, packing and transport.<ref name="CIWF">{{cite web|year=2005|title=The Welfare of Broiler Chickens in the European Union|last1=Turner|first1=J.|last2=Garcés L. and Smith|first2=W.|publisher=[[Compassion in World Farming]] Trust|url=http://www.ciwf.org.uk/media/3818904/welfare-of-broilers-in-the-eu.pdf|access-date=November 16, 2014}}</ref>

== World production and consumption ==
{{Main|Broiler industry}}
[[File:Meat Atlas 2014 Estimated chicken consumption.png|thumb|upright=1.25|Estimated chicken consumption per person in 2012]]
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&nbsp;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&nbsp;billion in 2004; of these, approximately 19% were produced in the US, 15% in China, 13% in the EU25 and 11% in Brazil.<ref name="CIWF" />

Consumption of broilers is surpassing that of beef in industrialized countries, with demand rising in Asia.{{needs update|date=February 2021}}<ref>''[[Meat Atlas]] 2014 – Facts and figures about the animals we eat'', p. 41, [https://www.foeeurope.org/sites/default/files/publications/foee_hbf_meatatlas_jan2014.pdf pdf]</ref> Worldwide, 86.6&nbsp;million [[tonnes]] of broiler meat were produced in 2014,<ref>{{cite report |title=Livestock and Poultry: World Markets and Trade |url=https://apps.fas.usda.gov/psdonline/circulars/livestock_poultry.pdf |date=October 11, 2018 |publisher=USDA |access-date=July 2, 2012 |archive-date=October 11, 2012 |archive-url=https://web.archive.org/web/20121011213233/http://www.fas.usda.gov/psdonline/circulars/livestock_poultry.pdf |url-status=live}}</ref> and {{as of|2018|lc=y}}, the worldwide estimation of broiler chick population was approximately 23&nbsp;billion.<ref>{{cite journal |title=The broiler chicken as a signal of human reconfigured biosphere |vauthors=Bennett CE, Thomas R, Williams M, Zalasiewicz J, Edgeworth M, Miller H, Coles B, Foster A, Burton EJ, Marume U |journal=Royal Society Open Science |volume=5 |issue=12 |article-number=180325 |date=December 2018 |doi=10.1098/rsos.180325 |pmid=30662712 |pmc=6304135}}</ref>

== Impacts of climate change ==
{{excerpt|Effects of climate change on livestock#Poultry|files=no}} 

== See also ==
{{Portal|Agriculture and Agronomy}}
*[[Cruelty to animals|Animal cruelty]]
*[[Animal welfare science]]
*[[Chicken]]
*[[Chicken tax]]
*[[Cobb 500]]
*[[Concentrated animal feeding operation]]
*[[Early feeding]]
*[[Intensive animal farming]]
*[[Poultry farming]]
*[[Ross 308]]
*''[[The Chicken of Tomorrow]]''
*[[Ayam Kampong]]

== References ==
{{Reflist|30em}}

== External links ==
{{Wiktionary}}
{{Commons category|Broilers (poultry)}}

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[[Category:Chicken crossbreeds]]
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