Melamine residues in eggs of laying hens exposed to melamine-contaminated feed

An experiment was carried out to determine melamine residual levels in eggs by feeding laying hens 200 or 1,000 mg of melamine/kg of diet. Each diet was offered in 3 replicate cages (10 laying hens/cage) from d 1 to 29, followed by a 9-d feeding of a withdrawal diet that contained no melamine. Two eggs were collected from each replicate cage each day for the determination of residual melamine levels after 1 d of feeding. The feeding of melamine resulted in a fast accumulation of melamine in eggs within 3 to 4 d, then maintained 2.00 to 3.88 mg/kg for 200 mg of melamine/kg of diet and 11.09 to 16.46 mg/kg for 1,000 mg of melamine/kg of diet. A withdrawal period of 4.0 d for 1,000 mg of melamine/kg of diet was required based on tolerance values established by the World Health Organization and no withdrawal period was required for 200 mg of melamine/kg of diet.