Influences of lead exposure on its accumulation in organs, meat, eggs and bone during laying period of hens

Elevating levels of environmental lead (Pb) results in serious hazards to health of animals and human beings. In this study, daily diet with three different levels of Pb (Pb nitrate at doses of 1, 10, and 100 mg/kg body weight) were fed to ISA Brown layers. It showed that the kidney and liver have the relatively high Pb concentration (2.34 and 0.51 ppm) after culture, while the meat has the Pb concentration as low as 0.07 ppm (lower than the standard of Codex Alimentarius). It was also confirmed that egg laying worked as a potential pathway for hens to excrete Pb as Pb concentrations in eggshell and yolk increased from 0.10 to 3.11 ppm. However, the Pb concentration in egg white remains at a safe level (<0.10 ppm). Furthermore, even the intake of low dose Pb can cause a decline of bone mineral density and bone strength. Raman spot and mapping analysis indicated that carotenoids content in humerus from the hens of high dose group increased significantly, which hence can be applied as an indicator for resist stress. The degradation of bone quality will further damage the health of laying hens. Therefore, Pb exposure not only toxifies organs and reduces physiological features (e.g., body weight and laying rate) instantly, but also hurts poultry via degrading bone quality in long term. Additionally, the probability of excessive Pb in poultry meat is less than those of viscera and eggs, indicating its low risk to food safety.