LAUSR

Abstract The raw materials used in poultry feed do not provide sufficient carotenoids to achieve the yolk pigmentation demanded by consumers, so color additives are included usually in the form of carotenoid-rich dried plant extracts. We fed thirty-two laying hens (ISA Brown) on diets supplemented with two genetically engineered maize lines (enriched in carotenoids or ketocarotenoids) to assess egg productivity and quality traits. Four different maize-supplemented diets were compared based on two genetically engineered maize lines (Ph3 and BKT), the white near isogenic wild-type line (M37W) and a commercial feed based on standard commercial (SC) yellow maize. Line M37W-Ph3 (Ph3) accumulates high levels of β-carotene, zeaxanthin and lutein, whereas line NSL76*BKT (BKT) is rich in astaxanthin and other ketocarotenoids. There were no significant differences among the diet groups in terms of egg weight, breaking strength, albumen height, Haugh units, or shell thickness, but there were significant differences in DSM scale values for yolk pigmentation (P