13-662: The Cambar is the first autosexing breed of chicken intentionally created, and the first autosexing breed of poultry in general. The Cambar was developed by Reginald Punnett and Michael Pease in 1929. The Cambar was a mixture of the Barred Plymouth Rock and the Gold Campine . The Cambar was first shown at the Third World Poultry Congress in 1930. The breed was standardized in 1947. Autosexing Auto-sexing breeds of poultry are those in which
26-553: A crest and to lay blue or blue-green eggs. The Legbar was the second auto-sexing chicken breed created by Reginald Crundall Punnett and Michael Pease at the Genetical Institute of Cambridge University , after the Cambar , which was created in 1929 by crossing barred Plymouth Rock with gold Campine birds. The Legbar arose from cross-breeding of Plymouth Rock birds with brown Leghorns , which at that time were two of
39-501: A different sex-determination system compared to mammals (X and Y). Male birds have therefore two Z-chromosomes while female birds have a Z- and a dwarfed w-chromosome. This means that phenotypically barred cocks can either have the B/B or the B/b+ genotype , while a barred hen always has to have a B/- genotype. The colour-sexing of Legbar chicks, however, is only possible because the male chicks have
52-563: A double dose of the sex-linked barring gene (genotype B/B), while the female chicks only have a single dose (genotype B/-), resulting in the observed down colours. The concept of an auto-sexing breed of chicken is due to the geneticist Reginald Punnett , who during the First World War had already proposed the technique of cross-breeding chickens carrying the barred gene (B) with others to produce sex-linked chicks with plumage differences that could easily be distinguished. Working at
65-420: A standards for the adult birds, the down colour and patterns are also standardised. Day-old male chicks can be distinguished from day-old female chicks by the down colour and the pattern they form. Female Legbar chicks in general have a broad very dark brown stripe extending over the head, neck and rump and a clear eye barring. The edges of the stripe are clearly defined and should not be blurred and blending with
78-553: The Genetical Institute of Cambridge University , he and Michael Pease cross-bred Golden Campines with barred Plymouth Rocks , resulting in the creation of the Cambar in 1928. About ten years later they produced the Legbar by crossing brown Leghorns with barred Plymouth Rocks. Other "Cambridge" breeds later developed were: Many other breeds were created in the same way, all making use of barred Plymouth Rocks to impart
91-462: The Legbar is an auto-sexing breed. Several other auto-sexing breeds or auto-sexing varieties of breeds exist, such as Plymouth Rock, Bielefelder Kennhuhn , Niederrheiner , and Norwegian Jærhøns . Most breeds that end with -bar, such as Welbar , Rhodebar , Brussbar or Wybar , are auto-sexing as well. The importance that auto-sexing plays in the Legbar breed is also reflected in the fact that, next to
104-641: The UK breeds on the watchlist of the trust; neither is considered "priority". The Legbar has three colour varieties : gold, silver and cream. The cream variant has a crest and lays blue, olive or green eggs. The Legbar is considered a rare breed by the Poultry Club of Great Britain and, until the Autosexing Breeds Association was re-formed, fell under the Rare Poultry Society . The Legbar
117-508: The barred gene: Legbar The Legbar is a rare British auto-sexing breed of chicken . It was created in the early twentieth century by Reginald Crundall Punnett and Michael Pease at the Genetical Institute of Cambridge University . They cross-bred American barred Plymouth Rock birds with brown Leghorns and created the gold and silver colour varieties . Pease created a cream Legbar by cross-breeding these with white Leghorns; later crossing with Araucanas caused this to have
130-581: The creation of the cream Legbar, a crested layer of coloured eggs for which a standard was drawn up in 1958. Within a short time it became very rare, but has since recovered. It is treated by the Poultry Club of Great Britain as a colour variety of the Legbar, but is considered by the Rare Breed Survival Trust to be a separate breed. Both the Legbar and the Cream Legbar are listed among
143-528: The ground colour, which is dark brown. A light head spot should be visible but is usually small. The male Legbar chicks in contrast have a much paler down shade and the pattern is blurred and washed out from head to rump. The marked difference between male and female chicks is due to gene dosage of the sex-linked barring gene ('barring' (B), 'nonbarring' (b+)). This gene is located on the Z-Chromosome of birds. Birds have different sex-chromosomes (Z and w) and
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#1732869326582156-696: The principal egg-laying breeds. As with the Cambar, they set out to breed a bird that would both have brown down and carry the barred gene (B) , so that chicks would have sex-linked plumage differences that could easily be distinguished. Standards for the gold and silver colour varieties were drawn up in 1945 and 1951 respectively. The cream Legbar was created by chance. Through cross-breeding of gold Legbars with white Leghorn stock, Pease had obtained some cream-coloured birds; their eggs were white, and they had no crest. An experimental crossing of these with some cream-coloured Araucanas from Punnett's laboratory led to
169-489: The sex of newly-hatched chicks can be determined from the colour and markings of the down . Some breeds of chicken , of goose and of domestic pigeon have this characteristic. The idea of such a breed is due to Reginald Punnett , who created the first auto-sexing chicken breed, the Cambar , at the Genetical Institute in Cambridge in 1928. Unlike sex-linked hybrids, such as 'red sex-links' or 'black sex-links' ,
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