The assessment of melamine and cyanuric acid residues in eggs from laying hens exposed to contaminated feed.

The aim of this study was to monitor the carry-over of melamine and its metabolite cyanuric acid from melamine-contaminated feed administered to layers into eggs. Ten experimental Isa Brown layers (36 week of age) were fed melamine-contaminated feed containing 100 mg of melamine per kg of feed. The duration of the experiment was 6 weeks. Eggs were collected during whole experiment. Analysis of eggs was done by a simple extraction of melamine and cyanuric acid residues, using a water-acetonitrile mixture and analysed by gas chromatography - triple quadrupole mass spectrometry. Melamine and cyanuric acid residues were detected in all eggs collected from the experimental layers, immediately after the first administration of melaminecontaminated feed. The mean concentrations of melamine in the egg yolk and egg white recalculated on a dry matter basis were 1.90 mg⋅kg-1 ± 0.158 and 10.84 mg⋅kg-1 ± 3.951 (P ≤ 0.01); the cyanuric acid contents were 6.54 mg⋅kg-1 ± 0.2.466 and 4.07 mg⋅kg-1 ± 0.909, respectively. Melamine and cyanuric acid were not detected in eggs from control layers. Concentrations of melamine and cyanuric acid in eggs decreased quickly after melamine feeding was stopped. Our results indicate that melamine undergoes biotransformation to cyanuric acid in the layer's body that also passed into the eggs. The results verified the presence of distribution metabolic pathway of melamine and its easiest transfer into egg yolk. Moreover, the biotransformation of melamine into cyanuric acid in eggs of layers was confirmed. [ABSTRACT FROM AUTHOR]