Distribution of carotenoids from the yolk to the tissues of the chick embryo11This research was funded by the Scottish Office Agriculture Environment and Fisheries Department

Laying hens were placed on either a control diet or a carotenoid-supplemented diet. The subsequent concentrations of carotenoids in the yolks of the newly laid fertile eggs (μg carotenoid/g fresh yolk) were 13.3 and 41.1 on the control diet and high-carotenoid diet, respectively. For the day-old chicks derived from the high-carotenoid group, the carotenoid levels in the yolk sac membrane, liver, and plasma were approximately 3 times greater than in the control group; however, the other tissues were less responsive. The proportion of lutein (% wt/wt of total carotenoids) was far lower in the liver of the chick than in the yolk. However, in the non-hepatic tissues the proportion of lutein was generally higher than in the yolk. This suggests that discrimination between different carotenoids may occur in the embryo. For the high-carotenoid group, the peroxidative susceptibility of extracts of the yolk, yolk sac membrane, and liver was decreased compared with samples from the control group. Thus, carotenoids may provide antioxidant protection to the tissues.