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Delayed-feathering in chickens consists of a genetically determined delay in the first weeks of feather growing, which occurs normally among the chicks of many chicken breeds and no longer manifests itself once the bird completes adult plumage. The difference between fast normal and delayed-feathering can be recognized in one-day-old chicks but is always more evident in 10- to 12-day-old chicks. Female chicks have a slightly faster feathering than males. Barely seen in breeds with fast normal-feathering, this characteristic is better observed in breeds with delayed feathering, like Barred Plymouth Rock.〔Hutt, F.B. Genética Avícola. Salvat Editores,S.A. 1ra.ed. España (1958)〕 Natal down color is not related to feathering speed, but in chickens of full-black adult plumage, chicks normally have shorter natal down than those from breeds of any other plumage color pattern 〔Kabystina, P.A. and Petrov, S. G. The genetics of down lengths in chickens (trans. title) Genetika Selekcija seljsk.-hoz. Zivotn. 1, 321-336, (1935)〕 being this shortening more obvious in the head and back. Feathering growth in the first weeks of life is genetically controlled by a few autosomal genes and a sex-linked gene.〔 Most of the genetical variation among breeds can be explained by the sex-linked gene ''K''. Autosomal genes retarding feathering growth are not typical in any particular breed. Because those genes are recessive, they need to be in homozygosity to manifest themselves, but as poultry farmers dislike bad-fledged birds, autosomal genes only subsist in very low frequencies. Contrarily, sex-linked delayed-feathering is very frequent, particularly in meat-type breeds like Brahma, Cornish, Cochin, Rhode Island Red, Wyandotte, Plymouth Rock and Orpington. Sex-linked genetic variation has proven to be very useful for the sex identification of one-day-old chicks in commercial hybrids. ==Sex-linked feathering== Sex-linked feathering is controlled by locus ''K'' on the sexual chromosome, with four known alleles in the following dominance order: ''K''n > ''K''s > ''K'' > ''k''+.〔McGibbon, W. H. A sex-linked mutation affecting rate of feathering in chickens. Poultry Science 56, 872-875 (1977)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Delayed feathering in chickens」の詳細全文を読む スポンサード リンク
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