本试验通过在奶牛饲粮中添加三聚氰胺下脚料，研究三聚氰胺对奶牛瘤胃液、血液、尿液、粪和奶中三聚氰胺残留浓度的影响，进而揭示三聚氰胺在奶牛体内的代谢途径。试验设计3个三聚氰胺添加水平(添加量分别为精料量的0.516%、0.860%和1.204%)，分为3个阶段进行试验，每个阶段都是相同的5头牛，同一阶段饲喂相同的试验饲粮。每个阶段试验期10 d，前7 d为预试期，后3 d为采样期。结果表明：尿、粪和牛奶中三聚氰胺的残留浓度随着三聚氰胺下脚料添加水平的增加而上升，其中添加水平最高阶段的牛奶中三聚氰胺的残留浓度为1.31 mg/kg，粪中三聚氰胺的残留浓度为3.30 mg/kg，尿中三聚氰胺的残留浓度为107.75 mg/kg。由此得出，三聚氰胺主要代谢途径是泌尿系统，而粪和牛奶只是辅助代谢途径。

This trail was conducted to study the effects of dietary supplementation of melamine byproducts on residual concentration of melamine in rumen fluid, blood, urine, feces and milk of dairy cows. The further object was to reveal the metabolic mechanism of melamine in dairy cows by single factor experiment. The supplemental levels in the concentrate were 0.516%, 0.860% and 1.204%, respectively. The experiment was divided into 3 phases with 10 days in each phase (7 days for pre-feeding and 3 days for sampling). The same 5 Holstein dairy cows were fed the same experimental diet in each phase. The results showed that the residual concentration of melamine in milk, feces and urine were all increased with the growing supplementation level. The concentration of melamine in the raw milk, feces and urine from the phase with the highest supplemental level were 1.31, 3.30 and 107.75 mg/kg, respectively. It is concluded that renal excretion is the primary metabolic pathway of melamine while defecation and lactation are only auxiliary pathways. ［Chinese Journal of Animal Nutrition, 2010，22（6）:1703-1708］