Associated effects of the roux plumage color mutation on growth, carcass traits, egg production, and reproduction of Japanese quail

After two generations of introgression of the sex-linked recessive roux color mutation into a commercial broiler Japanese quail line with wild-type plumage, growth, carcass, egg laying, and reproduction of birds were evaluated and compared for all types of birds produced (considering sex, line, and plumage). Usual sex differences were obtained for BW, with larger values in females and 5% sexual dimorphism. Weights were larger also in the pure commercial line, which had a higher hatching rate (HR) than the introgressed birds at 17 to 19 wk of age. Roux plumage was significantly associated with 3% lower BW and 30% less abdominal fat (AF) pad. Egg production was not influenced by the roux mutation, but egg weight (EW) was 2% lower. Characteristics associated with the roux gene are similar to those reported for the albino mutation, except for AF, which was not tested in albino quail. The similarity of the pleiotropic effects might result from some modification that the two mutations induce in an early step of a metabolic pathway involved both in coloration and in growth. From a practical breeding standpoint, the roux gene appears to be a interesting candidate gene for auto-sexing in quail production.