There is no reported method for the quantification of methylglyoxal in ruminal fluid. The methodreported here is based on the conversion of methylglyoxal to 6-methylpterin, followed by quantificationof the resulting pteridinic compound by fluormetric detection using liquid chromatography. Ruminalfluid was collected and preserved with 1 M HCl at -20
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C. Cation exchange prior to derivatizationwas used to eliminate possible interfering peaks. The detection limit of 0.125
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g/mL was calculated.The recoveries were >80%, and the coefficients of variation were <15%. This method has provento be rugged and accurate for the detection of methylglyoxal concentration in ruminal fluid collectedfrom cows fed diets deficient in
degradable intake
protein as a marker. Methylglyoxal is produced byruminal bacteria in response to low nitrogen levels in the
rumen. The ruminal methylglyoxalconcentration has the potential to be a useful marker to assess ruminal nitrogen status to aid inmore accurate diet formulation.Keywords: Methylglyoxal; HPLC; ruminants; nitrogen, carbohydrate