(OR16-02-26) Production System Influences Carotenoid and Polyphenol Concentrations in Egg Yolk

Objectives: Carotenoids and polyphenols are plant-derived phytochemicals associated with antioxidant activity and potential health benefits. In laying hens, the deposition of these compounds into egg yolk depends on dietary exposure. Pasture-raised systems provide seasonal access to diverse forage sources, which may alter yolk phytochemical concentrations compared to conventional caged systems reliant on formulated feed. The objective of this study was to quantify carotenoid and polyphenol concentrations in egg yolks from a pasture-raised system across the grazing season and to compare these values to conventional caged eggs.

Methods: Egg samples were collected monthly from a pasture-raised laying hen system in Ohio from May through December. Twelve conventional caged egg samples were collected at a single time point to serve as a production system control. Yolk samples were pooled and analyzed for individual and total carotenoids and polyphenols using liquid chromatography–mass spectrometry (LC–MS).

Results: Pasture-raised yolks exhibited significantly higher lutein (up to 8885 µg/100 g) and α-cryptoxanthin (2164 µg/100 g) compared to caged controls, 4283 µg/100 and 188 µg/100 respectively (p < 0.05). Vitamin A metabolites varied seasonally, peaking mid-season. Polyphenols such as chlorogenic acid, hydroxybenzoic acid, and kaempferol-3-glucuronide, were significantly elevated in pasture-raised yolks, with notable seasonal fluctuations (p < 0.05). Several phenolic compounds, including chlorogenic acid and 4-hydroxybenzoic acid peaked mid-season, indicating seasonal trends in forage availability.

Conclusions: Egg yolk phytochemical composition is influenced by production system and seasonal forage access. Pasture-raised hens exhibited enhanced deposition of plant-derived carotenoids and polyphenols relative to conventional caged controls, with concentrations varying across the grazing season. These results support the concept that forage diversity and seasonal dietary exposure can translate into measurable differences in the bioactive profile of animal-derived foods.

Funding Sources: The Greenacres Foundation provided funding for this study.