| Content:Melamine (1,3,5-triazine 2,4,6-triamino-s-triazine) is a common chemical material used primarily for the production of melamine resins.Because of its high cotent nitrogen(66%),melamine was added in the feed deliberately to get more profit,which brought a series of food pollution questions.A number of pets and children poisoned,even died. At present,studies on melamine are mainly focused on detection method and toxicity,deposit and clearance of melamine in laying hens are still not reported.In this paper,the deposit and clearance of melamine in eggs,tissues and excretion by high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) were studied systemically,which offers foundation for eggs production.Experimental 1 Deposit and Clearance of Melamine in Eggs of laying hens.Two hundred and twenty eight Hy-line Variety Brown twenty eight weeks old were randomly divided to seven treatments with six replicates .The group of control with eight hens in each replicate,received corn-soybean meal diet ,the other groups,six hens in each replicate,received the same basal diet supplement with 1,2,5,25,50,100 mg/kg melamine respectively. The feeding trail lasted six weeks, deposit and clearance of melamine cost three weeks respectively.. In deposit experiment,on 1,2,3,4,5,6,7,8,9,10,11,13,15,17,19,21 d after administrating melamine,on 1-15d withdrawling melamine ,eegs in each replicated were collected to detect melamine and cyanuric acid.by UPLC-MS/MS. Recored the amount of melamine intook and the amount in eggs.Melamine excretion efficiency from feed to eggs were calculated . Effect of melamine on production performance were recorded when the hens fed diet with or without melamine.The result showed that 1) In deposit experiment, melamine was absorded quickly and found in the eggs the first day. the concentration of melamine in eggs of group 1,2,5,25,50,100 mg/kg melamine reached the maximum at 8,10,15,17,17,17d after first ingestion Linear responses were exhibited by the melamine concentration between eggs and feeds..2) In clearance trail, when withdrawling of melamine, the concentration of melamine in eggs were declined gradually. concentration of group 1,2,5,25,50,100 mg/kg melamine came lower than LOQ at 5,5,5,6,7,7d. 3)Melamine excretion efficiency in the eggs is highest in the control group and lowest in the group of 100mg/kg melamine,The highest melamine excretion efficiency In the treatment is 1.967%. It had no significant effect on production performance when the hens fed diet with or without melamine.Experimental 2 Deposit and Clearance of Melamine in Tissues of Laying Hens One hundred and forty-four Hy-line Variety Brown twenty eight weeks old were randomly divided to three groups with six replicates .Each replicate had eight eggs.The control group received corn-soybean meal diet and the treatment groups received the same basal diet supplement with 50,100 mg/kg melamine respectively. The feeding trail were fed melamine from Day I to 21 followed by a 96-h withdrawal period. On 3,7,14,21d and 8,24,48,96h,one laying hen per replicate was killed tissue samples from the breast meat,liver,kidney and plasma and excretion were collected,on 19d egg white and yolk of eggs in each replicate were separated,which were all prepared for the determination of residual melamine and cyanuric acid levels. Digestibility of melamine were calculated by the detection of Cr2O3 in feed and excretion.The result showed that 1) In deposit trail,the concentration of melamine in plasma,muscle,liver and kidney in the group of 100 mg/kg melamine reached the maximum all at 21d ,while in the group of 50 mg/kg melamine they reached the maximum are at 7d,14d,14d,21d respectively. The concentration of melamine in the excretions of treatment groups reached the maximum both at 3d.The concentration of melamine in kidney was significantly higher than muscle and liver at 3,7,14,21d ,while it had no significant difference between muscle and liver .2) In clearance trail, the concentration of melamine in muscle,liver and kidney in the group of 100 mg/kg melamine declined below the limit of detection at 24h since withdrawl melamine. while in the group of 50 mg/kg melamine they declined below the limit of detection(LOD) at 8,8,24h respectively..Melamine was still in plasma at 96h after withdrawl. Kidney clears melamine fastest in the tissues.3)From digestibility,it can concluded that after 24h withdraw period ,most of melamine had been eliminated,but melamine was not completely cleared after 96h withdraw period.4)In the whole trail, the two treatment groups had no significant difference on concentration of cyanuric acid in excretions.5)melamine exists in egg white and yolk ,and egg white is more than yolk.Experimental 3 Effect of Melamine on Production Performance,Follics Development and Follics DepositionsTwenty-four Hy-line Variety Brown forty-two weeks old were randomly divided to two groups with twelve replicates .The treatment groups was fed the diet containing 100 mg/kg melamine. On 17d,ovary were collected weighted and different follics were separated for the determination of melamine.The result showed that It had no significant effect on follics development,different level of follics all had melamine,which accumulated gradually in laying hens and reached steady. |
