State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2010 Oct;27(10):1372-9. doi: 10.1080/19440049.2010.498795.
The objective of this study was to assess the carry-over of melamine from feed into eggs and body tissues of laying hens. In the first experiment, laying hens were supplied with feed added at 0, 1, 2, 5, 25, 50, and 100 mg kg(-1) of melamine for 21 days followed by a depletion period to observe the residues of melamine in eggs. In a second experiment, laying hens were allocated 0, 50, and 100 mg kg(-1) melamine to determine levels of melamine in body tissues. Melamine and cyanuric acid were simultaneously analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the diet as well as in eggs and body tissue. In the first experiment, melamine appeared in the egg within 24 h after first ingestion of the melamine at 5, 25, 50, and 100 mg kg(-1). Melamine concentration in egg reached a maximum of 2.34 mg kg(-1) within 17 days after exposure of 100 mg kg(-1) melamine, and the carry-over rate for melamine from feed to the eggs was 1.21%. In the second experiment, melamine was detected in tissues within 3 days after exposure; the maximum concentration of melamine residues occurred in the 100 mg kg(-1) group and was as follows: egg (1.83) > kidney (1.21) > breast muscle (0.86) > liver (0.70) > serum (0.42). The melamine level in egg albumen was about twice that of egg yolk. Melamine levels in laying hens decreased rapidly with withdrawal from feed, but melamine only declined to undetectable levels in the egg at day 6 and in tissues at day 4 after last ingestion of 100 mg kg(-1). It can be concluded that a pathway exists for the transmission of melamine from feed to egg and body tissues and the carry-over rate of melamine is low, and that melamine is not metabolized into cyanuric acid in laying hens. A positive relationship exists between exposure levels and eggs or tissues, but no direct relationship between the exposure time and measured levels of melamine in eggs and tissues. The current Chinese limit for melamine in feed and feed material of 2.5 mg kg(-1) established on 8 June 2009 is sufficient to ensure that levels in eggs, breast muscle, liver as well as kidney will not exceed the limit of 2.5 mg kg(-1) in foods other than infant formula introduced by many countries including China.
本研究旨在评估三聚氰胺从饲料向产蛋母鸡的鸡蛋和体组织中的转移情况。在第一个实验中，母鸡连续 21 天摄入 0、1、2、5、25、50 和 100mg/kg 的三聚氰胺饲料，然后进行排料期以观察鸡蛋中的三聚氰胺残留情况。在第二个实验中，母鸡分别摄入 0、50 和 100mg/kg 的三聚氰胺，以确定体组织中的三聚氰胺水平。通过液相色谱-串联质谱法（LC-MS/MS），同时对饲料、鸡蛋和体组织中的三聚氰胺和三聚氰酸进行分析。在第一个实验中，在摄入 5、25、50 和 100mg/kg 三聚氰胺后的 24 小时内，母鸡的鸡蛋中就出现了三聚氰胺。暴露于 100mg/kg 三聚氰胺后 17 天，鸡蛋中的三聚氰胺浓度达到最大值 2.34mg/kg，饲料到鸡蛋的三聚氰胺转移率为 1.21%。在第二个实验中，暴露后 3 天就在组织中检测到了三聚氰胺，100mg/kg 组中三聚氰胺残留的最大浓度如下：蛋清（1.83）>肾脏（1.21）>胸肌（0.86）>肝脏（0.70）>血清（0.42）。蛋清中的三聚氰胺含量约为蛋黄的两倍。母鸡停止采食后，三聚氰胺水平迅速下降，但在停止摄入 100mg/kg 三聚氰胺后的第 6 天，鸡蛋中三聚氰胺的含量和第 4 天组织中的三聚氰胺含量才降至无法检测的水平。可以得出的结论是，三聚氰胺从饲料向鸡蛋和体组织的传递存在途径，三聚氰胺的转移率较低，且在产蛋母鸡中三聚氰胺不会代谢为三聚氰酸。暴露水平与鸡蛋或组织之间存在正相关关系，但鸡蛋和组织中三聚氰胺的暴露时间与测量水平之间没有直接关系。中国于 2009 年 6 月 8 日规定的饲料和饲料原料中三聚氰胺的限量为 2.5mg/kg，足以确保鸡蛋、胸肌、肝脏和肾脏中的三聚氰胺含量不会超过包括中国在内的许多国家规定的婴儿配方食品以外食品中 2.5mg/kg 的限量。
