Effect of the source and level of carotenoids in diets on their retention in eggs

The lutein and zeaxanthin deposition in egg yolks of hens was evaluated. The effects of various levels of extracts from Mexican marigold flowers in hen diets were compared in Experiments 1 (from 0 to 350 mg/kg) and 2 (from 0 to 950 mg/kg). In Experiment 3, the sources of carotenoids such as lutein (250 mg/kg) and Chlorella (12.5 g/kg) were examined. All three experiments were conducted using brown egg layers housed in enriched cages. The lutein concentrations in yolks were increased (P < 0.05) from 0.141 to 0.232 mg/60 g of egg (Experiment 1) and from 0.096 to 0.283 mg/60 g of egg (Experiment 2). A similar trend was observed for zeaxanthin. In Experiments 1 and 2, the zeaxanthin content increased from 0.096 to 0.150 mg/60 g of egg and from 0.046 to 0.200 mg/60 g of egg, respectively. However, the retention of lutein and zeaxanthin decreased in a dose-dependent manner from 55.8 to 33.0% and 49.1 to 29.3%, respectively, in Experiment 1 and from 81.2 to 23.3% and 57.0 to 21.6%, respectively, in Experiment 2. In Experiment 3, both the treated groups had greater lutein and zeaxanthin contents in the yolks. The ratio of lutein in the yolks from hens fed lutein to those from hens fed algae was 2.7 : 1 (1.044 and 0.382 mg/60 g of egg). Overall, 14.0 and 16.4% of lutein and 13.7 and 15.3% of zeaxanthin was retained in the eggs of hens fed lutein and algae, respectively. The concentrations of carotenoids in hen egg yolks depend on dietary intake, and the retention of carotenoids decreases with increasing dose. A higher carotenoid retention in the yolks was found when the hen diets were supplemented with the Mexican marigold extract than when Chlorella or pure lutein were used as supplements.