Genetic Analyses for the White-Tailed Character of the Chabo (Japanese Bantam)

Abstract

In the Chabo (Japanese Bantam) breed of native Japanese chickens, there are birds that have buff-like plumage. This plumage shows yellowish brown at the trunk and white for all the tail feathers and a part of the primaries. In other words, this plumage occurs when areas, normally black for “buff columbian” plumage are replaced by white ones. Genetic analyses revealed that the gene controlling the appearance of the white area is an incompletely dominant autosomal gene. The homozygous condition for the mutant gene completely inhibits the expression of black pigmentation, leading to the replacement of black areas with pure white ones. The inhibition effect in the heterozygote however, is incomplete, resulting in the white areas (feathers) that have a slight gray tinge and many minute gray or black speckles. The mutant gene also has a weak effect in inhibiting the expression of brown color. Furthermore, when birds have the mutant gene with a wild-type genetic background for other plumage color genes, they exhibited the “red-pyle” plumage pattern. Therefore, there is a high possibility that the mutant gene expressing white areas (feathers) in the Chabo is identical to the known dominant white (I) gene, because the effect and mode of inheritance of the mutant gene possessed by the Chabo are quite similar to those of the I gene. This could be the first finding of a dominant mutant gene controlling white plumage in Japanese fancy fowls.