Light down lethal: a new autosomal recessive down color mutation in Japanese quail.

A new plumage color mutation of Japanese quail (Coturnix japonica) was named "light down lethal" based on its light coloration of neonatal plumage and almost total mortality by 3 weeks of age. Prehatch mortality of the light down lethal was also higher (36.8%) than the wild type (8.2%). The majority of the light down lethal chicks that hatched died within 1 week of age. Among the 103 light down lethal chicks that hatched, only two males survived to adulthood and reproduced normally. Their adult mutant plumage was very similar to that of the wild type. The mutant down showed the same striped pattern on the dorsal surface as the wild-type chick, but the color of the stripes was lighter than the wild type. Genetic analysis revealed that the mutant phenotype is controlled by an autosomal recessive gene. The proposed gene symbol is ldl.