The influence of the white-wing feather plumage gene Ww on various quantitative traits in chickens

The white-wing plumage color gene Ww which acts as an embryonic lethal in homozygotes was studied to determine its pleiotropic effects on various quantitative traits. Two groups of birds Ww/ww+ and ww+/ww+ were compared for mortality, body weight, age to sexual maturity, egg production, egg weight and shape, and egg shell thickness. During 0 to 8 weeks of age, the Ww/ww+ birds showed three times greater mortality than did the ww+/ww+ birds. From 8 to 71 weeks of age their mortality was similar, although during the 36 to 71 week period the Ww/ww+ birds did show a somewhat higher level of mortality. The cause of the mortality was not determined. Body weight was consistently depressed for the Ww/ww+ birds; however, it was not always significantly so. No significant differences were noted among the other traits measured.