Poultry diets containing (keto)carotenoid-enriched maize improve egg yolk color and maintain quality

摘要

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 beta-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 < 0.001) that were higher in the Ph3 (10.08) and BKT (11.38) groups than the SC (4.22) and M37W (<= 1) groups. At the end of the trial, the total yolk carotenoid content was highest in the Ph3 diet group, followed by BKT, SC and M37W diet groups (56.5, 26.18, 11.54 and 1.81 mu g/g freeze-dried yolk, respectively). The Ph3 yolks were enriched in beta-carotene and beta-cryptoxanthin (pro-vitamin A carotenoids) whereas the BKT yolks accumulated astaxanthin and other ketocarotenoids. The diets had no detrimental effects on the health of the hens. We conclude that (keto)carotenoid-enriched maize enhances the (keto)carotenoid content and color of yolks and can replace the color additives used routinely in poultry feed formulations.