Corn hybrid influences carotenoid profile in eggs
When including in the diet of laying hens, yellow corn is rich in carotenoids that contribute to the vibrant color of egg yolk. These carotenoids also exert antioxidant, anti-inflammatory, antibacterial and immunomodulatory effects that benefit both the hens consuming yellow corn as well as consumers of their eggs.
In order to improve yolk pigmentation and the nutritional value of table eggs, carotenoid bioavailability needs to be considered. Recent research programs have focused on understanding and improving carotenoid bioavailability, but there has been little data on the effects of dietary micronutrients such as vitamins and minerals, which share common digestion steps and absorption mechanisms with corn carotenoids.
Researchers with the University of Zagreb in Croatia and Harper Adams University in the U.K. conducted a study to investigate the influence of vitamin A supplementation level and trace mineral form (inorganic or organic) on the content and deposition efficiency of carotenoids in the egg yolk of laying hens fed diets differing in two commercial corn hybrids. Their results were recently published in Poultry Science.
The corn hybrids used in the study were dent corn varieties that differed in grain hardness, carotenoid profile (similar carotenoid content levels), carotenoid in vitro bioaccessibility and deposition efficiency of carotenoids into egg yolk. Each corn hybrid was assigned to one of three vitamin A levels (5,000, 10,000 or 20,000 IU/kg) and either inorganic or organic trace minerals, creating 12 dietary treatments in a 2 x 3 x 2 factorial design.
The study used 252 laying hens beginning at 18 weeks of age housed in 84 enriched cages (seven cages per treatment). The study lasted 63 days and included a 20-day stabilization period and a 49-day sampling period.
According to the researchers, the tested hybrids significantly differed in the content of total and individual carotenoids in egg yolk, with the exception of except β-cryptoxanthin. Lutein was the main carotenoid in the soft-type hybrid and zeaxanthin in the hard-type one.
Lower vitamin A levels tended to increase the yolk content of provitamin A carotenoids and the deposition efficiency of all carotenoids for both hybrid types. Furthermore, the highest lutein content in egg yolk was found when the soft-type hybrid was supplemented with the lowest vitamin A level.
Trace minerals showed a relatively small effect on carotenoid content and deposition efficiency. However, a significant hybrid x vitamin A x trace mineral interaction existed because the hard-type hybrid had the highest deposition efficiency of all carotenoids except α-cryptoxanthin when diet was supplemented with organic trace minerals and the lowest vitamin A level, the researchers said.
The researchers attributed the differences in yolk carotenoid content and deposition efficiency to differences in diet composition – namely corn hybrid – as feed intake, egg production and yolk weights were similar across treatments.
The total carotenoid content in the yolks from the studied treatments was higher than the reported ranges for biofortified and commercial corn diets.
The results also suggest that organic trace minerals can improve the utilization of most carotenoids from hard-type corn grain, but factors such as dietary fatty acid profile could influence the deposition of carotenoids in addition to the supplementation of vitamin A and trace minerals.
What does this mean for producers?
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Carotenoids are important sources of bioactive compounds that provide health benefits to hens and consumers of egg products.
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Corn hybrid, specifically hardness, can influence the carotenoid profile of laying hen diets.
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Trace mineral form may affect carotenoid deposition efficiency in eggs.
The full paper, “Effect of supplementing corn diet for laying hens with vitamin A and trace minerals on carotenoid content and deposition efficiency in egg yolk,” can be found in Poultry Science and online here.
DOI: 10.1016/j.psj.2025.104843
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