Tissue Deposition and Residue Depletion in Lambs Exposed to Melamine and Cyanuric Acid-Contaminated Diets

Many countries have introduced maximum residue limits for melamine in foods since its adulteration in infant formula in China. However, more animal feeding studies are needed to understand the fate of melamine-contaminated animal feed. In this study, the melamine contents in tissues and serum were tested using LC-MS/MS for up to 60 days for lambs fed with diets containing 2-100 mg of melamine per kg of diet. A higher dose of melamine in the diet resulted in a higher concentration in tissues and serum, with the maximum melamine content in the kidney. When cyanuric acid was coadministered at an equal concentration to that of melamine, the deposition of melamine in lambs was similar to the treatment with melamine only and was much higher than the deposition of cyanuric acid. When melamine was withdrawn from the diet, melamine concentrations decreased below 20 mu g/kg in all tissues after 4 days. The present study may provide available information for future work about the risk assessment of melamine to human health.