Influence of caponization on skin pigmentation of male broilers.

Two experiments were conducted to investigate the influence of caponization on skin pigmentation. Male broiler chicks were divided into caponized, sham-operated, and intact treatment groups with surgery performed at 3 weeks of age (Experiment 1) or 1 week of age (Experiment 2). All chicks were provided with corn-soy broiler diets ad libitum. In Experiment 2, an additional 37.4 mg of total xanthophyll was added per kilogram of finisher diet. At 7 weeks of age, birds were processed, comb size was scored, and the gonadal area was examined to identify partially caponized or improperly sexed birds. Caponized, sham-operated, and intact carcasses for analysis totaled, respectively, 28, 25, and 18 in Experiment 1 and 59, 33, and 30 in Experiment 2. Skin pigmentation was measured by reflectance colorimetry on the anterior portion of the lateral feather tract, on the same area of breast skin after removal from the carcass, and on shank skin removed from the leg. No differences were found in skin lightness (L), redness (a), or yellowness (b) between the treatment groups. These results indicate that pigmentation differences between male and female broilers are not likely to be due to differences in testicular activity.