Editing Broiler (section)

== 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.|url-status=dead|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|url-status=dead}}</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|url-status=dead}}</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" />