Effects Of The Melamine With Cyanuric Acid On The Health And Residues In Laying Hens

The study was conducted to investigate the effects of melamine (MEL) and cyanuric acid (CYA) on laying performance and functions of liver and kidney, and their residues and elimination profiles in eggs and tissues of laying hens. A total of 126 Rohman 78-week-old laying hens were randomly allotted to 7 treatments with 9 replicates (2 birds per replicate) in a single factor assignment. The 7 dietary treatments included:the corn-soybean basal diet (Trt 1, control), and the basal diets supplemented with 5 mg MEL/kg,15 mg MEL/kg, and 30 mg MEL/kg,5 mg MEL/kg+1.667 mg CYA/kg,15 mg MEL/kg+5 mg CYA/kg, or 30 mg MEL/kg+10 mg CYA/kg, respectively. The experiment lasted 35 d. From 1 to 21, all replicates in each treatment were fed different treatment diet (intoxication peroid). From 22 d to 35 d,6 replicates of each treatment fed the basal diet for withdrawal peroid (1 to 14 d), and 3 replicates continue to fed different treatment diets (intoxication peroid). Egg quality was determined On d 21, the MEL and CYA concentrations were determined in eggs collected on 1,3,5,7,10,14,21,28,35 d (intoxication period) and 1,3,5,7,10 d (withdrawal period), in liver, kidney, plasma, and breast muscle collected on 21,35 d (intoxication period) and 7 d (withdrawal period).The results showed as follows:(1) The MEL supplementation at 5 to 30 mg/kg without or with CYA at 1.667 to 10 mg/kg had no significant effect on the performance and egg quality of laying hens (P>0.05).(2) MEL and CYA supplementation significantly increased the concentration of UA on d 21. Moreover, serum UA concentration was higher in layers diet contain the combination of MEL and CYA. Dietary MEL had damaged kidney to some extrent; the liver,kidney and oviduct magnum in hens fed diets supplemented with MEL and CYA had heavier damage than those in MEL supplementation groups, and the higher dosage of MEL in the diet, the more injury to the organ.The most serious group was supplemented with 30 mg/kgMEL and 10 mg/kg CYA group. Hepatic cells disorder with abnormal lobular architecture, unclear hepatic cord and large numbers of irregular or round vacuole in liver cytoplasm were observed in the liver, and swelling epithelial cells in renal tubule, blister denaturation and even light congestion of partial glomerulus were observed in the kidney. The epithelial of oviduct magnum became more shorter, submucosal acinar tissue edema, acinar cavity were widened, cell vacuolar degeneration, the secretory granules in the acinar lumen was significantly reduced.(3) The contents of MEL in the eggs and tissues were increased (P<0.05) with the dietary MEL increasing, but were not influenced by CYA supplementation. No CYA residues were detected in eggs and tissues of laying hens.(4) No MEL residues were detected in plasma, egg and tissues at 3,5 and 7 days after withdrawl, respectively. After elimination of MEL and CYA for 7 days, the contents of serum UA recovered to the control levels, and no significant lesions in the liver,kidney and oviduct magnum were observed.In conclusion, the MEL supplementation at 5 to 30 mg/kg without or with CYA at 1.667 to 10 mg/kg by the ratio of 3:1 had no significant effect on performance of laying hens; MEL can destroy the liver and kidney of laying hens,and the toxicity of supplementation with MEL and CYA heavier than supplementation with MEL alone MEL contents in eggs and tissues were increased with the increasing dietary supplemental level (P<0.05), and the concentration of MEL was highest in kindy.