Wu et al. 2022 — Selenized yeast, laying hen performance, and heavy metal accumulation in eggs
This 12-week controlled feeding study measured the protective effects of selenized yeast supplementation on laying hen performance and on the accumulation of cadmium, lead, mercury, and chromium in egg yolk and egg white. Hens were orally gavaged with Cd, Pb, Hg, and Cr at fixed doses, with and without selenized yeast co-supplementation. Metal concentrations in egg yolk and egg white were measured by graphite furnace atomic absorption spectrometry (GFAAS) for Pb and Cd and by direct mercury analysis (DMA-80) for Hg. The study found that selenized yeast supplementation significantly reduced metal accumulation in egg tissue compared to the heavy-metal-only control group, and it improved egg production rate and egg quality parameters.
Key numbers
- Egg yolk Pb: ranged from approximately 0.44b mg/kg dry matter (lowest treatment group) to 1.14a mg/kg dry matter (Pb-gavage only, no Se), n=160 hens across groups; values differ by treatment group per one-way ANOVA.
- Egg yolk Cd accumulation also reported; Hg and Cr measured in both yolk and white fractions.
- Experiment: 160 Hy-Line brown laying hens, 12 weeks, China.
- Analytical methods: GFAAS (Pb, Cd, Cr), DMA-80 (Hg).
Methods (brief)
Controlled gavage feeding trial in China. Heavy metals administered via oral gavage; selenized yeast co-supplemented at graded doses. Egg fractions (yolk and white) analysed separately. GFAAS used for Pb, Cd, Cr; DMA-80 for total Hg. Dry weight basis for metal concentrations in tissue.
Implications
Certification: Documents that laying hens accumulate Pb, Cd, Hg, and Cr into egg yolk and egg white from dietary exposure; relevant for egg product categories and poultry supply-chain risk. Courses: Demonstrates metal transfer from feed to edible egg tissue; illustrates how dietary interventions (selenized yeast) can modulate accumulation. App: Eggs can carry Pb, Cd, Hg, and Cr at detectable concentrations when hens are exposed through feed; this study is a dietary-stress model, not an occurrence survey, so values reflect gavage dosing rather than real-world contamination levels.