Carcase characteristics of a heavy Japanese quail line under introgression with the roux gene.

1. The roux plumage sex-linked recessive gene may be used for early sexing of Japanese quail in crossbreeding production systems with wild-type and roux lines. However, associated effects of the gene on carcase and meat composition need to be assessed. 2. Quail carcases from pure Line K males and females (100% K), a heavy meat line which was used as the recipient line for the introgression of the roux gene, and from same-age roux or wild-type females from the second generation of introgression (75% K) were dissected. The effects of sex, line and plumage colour on carcase components and on protein and lipid contents of various tissues were estimated. 3. Expected sex differences in carcase weights were obtained, with marginally higher values for females. However, weights of parts and carcase yield (ratio of empty carcase weight without head, neck and feet over live body weight) were similar for both sexes in pure Line K which had a 68% carcase yield. Lipid contents in leg meat were higher in males (3.1%) than in females (2.7%). 4. The roux gene did not seem to have any major impact on carcase parts or composition. However, in roux birds, leg skin was marginally higher in lipids and pectoralis major lower in proteins than in wild-type ones.

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.