A comparison of different analysis methods for milk urea nitrogen

The objective of this study was to develop a reliable and cheap method to determine of milk urea nitrogen and compare some other instrumental methods. Two trials were conducted. In first trial, a milk urea nitrogen testing method was designed by modifying some methods developed for ammonia nitrogen testing method. Several studies were performed for the validation of method. By using standard solutions some applications such as determinability, recovery, repeatability, test of various analyzers and devices, limit of quantification were performed. Recovery of added urea averaged 99.38 %. In second trial, 105 individual milk samples from a dairy farm was analyzed for milk urea nitrogen by modified indophenol, infrared, and MiniFoodLab methods. The means of milk urea nitrogen obtained from three different methods were 23.87, 21.59, and 23.92 mg/dl, respectively. There was a positive correlation between modified indophenol and infrared methods.