Sex-links are
crossbred 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 ...
s whose color at hatching is differentiated by sex, thus making
chick sexing an easier process. Sex-links come in several varieties. As hybrids of laying or dual-purpose breeds infused with extra vigor via
heterosis
Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions o ...
, sex-links can be extremely good egg-layers which often produce 300 eggs a year or more depending on the quality of care and feed. The color of their eggs vary according to the mix of breeds, and blue-green eggs are possible.
Chicks of a single breed that are similarly sex-linked are called autosex chickens, a term developed to differentiate between
sex linkage
Sex linkage describes the sex-specific patterns of inheritance and expression when a gene is present on a sex chromosome (allosome) rather than a non-sex chromosome ( autosome). Genes situated on the X-chromosome are thus termed X-linked, and ...
in purebred chickens versus sex linkage in crossbreeds.
Sex-link types
Many common varieties are known as the black sex-link (also called black stars) and the red sex-link (also called red stars). More specific variety names are common as well.
* Black sex-link like "Black rocks" are a cross between unique specially bred hybrid strains of
Rhode Island Red rooster (but any non-white and non barred rooster may be used for other black sex-link crosses) and a
Barred Rock hen (which carry both extended black and barring genes).
* Red sex-links are a cross between a Rhode Island Red or New Hampshire rooster and a
White Rock (This variety pair is known as a
Golden Comet),
Silver Laced Wyandotte, Rhode Island White, or
Delaware
Delaware ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic and South Atlantic states, South Atlantic regions of the United States. It borders Maryland to its south and west, Pennsylvania to its north, New Jersey ...
hen.
Examples of a red-linked breeds include the
Red Shaver and
ISA Brown sex-links which are found in Canada.
White birds should not be used in sex-linked crosses because white colour allele is sometimes dominant and sometimes recessive.
Sex-linked Information
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Gallery
File:A_Red_Sex_Link_Rooster_"Freckles".jpg, A red sex-link rooster
File:Black Rock Hen 'Blackie'.jpg, A Black Rock hen
File:RedStarhen.jpg, A red sex-link pullet
File:Beautiful Roo by sejr.jpg, A black sex-link rooster
File:Shipped pullets.jpg, Shipped pullets
File:Linda Lee, a pet Red Sex Link hen (2004).jpg, Red sex-link hen
File:Black Sex Link Chicken.JPG, Black sex-link rooster
See also
* ZW sex-determination system
The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatwor ...
* List of chicken breeds
There are hundreds of chicken breeds in existence. Domesticated for thousands of years, distinguishable breeds of chicken have been present since the combined factors of geographical isolation and Selective breeding, selection for desired charact ...
References
External links
Chicken crossbreeds
{{Poultry-stub