Subjective and Colorimetric Evaluation of the Xanthophyll Utilization of Natural and Synthetic Pigments in Broiler Diets

Sexed day-old broiler-type chicks were placed on iso-caloric, iso-nitrogenous diets that derived pigment from different sources. The 1548 birds received xanthophyll in increments of 7.7 and 12.1 mg./kg. from diets containing (1) yellow corn, (2) yellow corn and alfalfa, (3) yellow corn and corn gluten meal, (4) yellow corn, alfalfa and corn gluten meal, (5) alfalfa, (6) corn gluten meal and (7) alfalfa and corn gluten meal. Two synthetic pigments, Avizant (citranaxanthin) and canthaxanthin, were added to the natural pigment diets as well as to a xanthophyll-free diet at levels of 4.4 and 8.8 mg./kg. of the finished feed. A standard was prepared by the addition of 5, 10, 20, 30 and 40 mg./kg. of beta-apo-8′-carotenoic acid ethyl ester (apo-ethyl ester) to the xanthophyll-free diet. All birds were evaluated visually by the Roche Yolk Colour Fan and the Ralston Purina Skin Pigmentation Guide and objectively by the IDL Color-eye® (Signature Model), a reflectance colorimeter. Results indicated that corn gluten meal and yellow corn had a higher xanthophyll utilization than did alfalfa. Canthaxanthin was utilized better than was Avizant. There appeared to be differential utilization of xanthophyll in that shanks were better pigmented than the skin. The reflectance colorimeter produced more consistent results than visual scoring and seemed to be superior in the evaluation of red pigment.