Study On The Residue And Withdrawal Of Melamine In The Egg And Tissues Of Laying Hens, And The Effect Of Melamine On Health Of Laying Hens

To investigate the residue and withdrawal of melamine in eggs and hen tissues, and the effect of melamine on the hematology, histopathology and production performance of laying hens, seventy-two Roman laying hens were administrated with 125-2000 mg melamine per kg diet for 35 days. The melamine concentration in egg, muscle, liver, kidney, muscular stomach, duodenum, uterus, ovary and blood plasma was determined by HPLC-UV methods. A higher dose of melamine in the diet corresponded to a higher concentration in tissues and egg. The concentration of melamine in egg, muscle, liver, kidney, muscular stomach, duodenum, uterus, ovary and blood plasma was in the range of 1.07-28.72μg/g,0.43-9.30μg/g,0.53-6.86μg/g,1.28-21.65μg/g,0.41-7.29μg/g,0.29-2.77μg/g,0.48-6.87μg/g,0.50-9.08μg/g and 0.79-7.57μg/g, respectively. When melamine was withdrawn from the diet, melamine concentration in hen tissues fell below 2.5 mg/kg at day 10, and no residue was determined in egg and tissues at day 7 and day 20 respectively. The creatinine concentration in plasma increased (P=0.107) as melamine concentraition increased.There was no significant difference on serum GOT and GPT activity among different treatments. Hens fed the melamine supplementation diet for 35 days developed hyperemia and tumefaction of renal glomerulus, denaturation and tumefaction of renal tubule epithelial cells,and the renal crystals were found in 1000 mg/kg and 2000 mg/kg melamine group. There was no significant difference on feed consumption, laying ratio, egg white haugh unit and eggshell,but the egg weight, egg yolk comparative weight and egg yolk color was reduced.In conclusion, the melamine residue concentration and withdrawl times in eggs and tissues of laying hens were raised as melamine concentration in diet increased. The melamine induced renal lesion, and the extent of kidney cortex and kidney medulla damage was increased with the doses of melamine, the crystals in renal tubule when the additional concentration was 1000-2000 mg/kg.