Milk urea nitrogen: Quality control of testing, individual cow factors, and correlations with bulk tank testing

Milk urea nitrogen (MUN) has been used to assess the nutritional status of dairy cows. However, in any program using MUN values to monitor nutrition in a dairy herd, other factors need to be evaluated and considered. These factors include the reliability of method of determination of MUN, the role of a variety of cow level factors and seasonal variation.

The first objective of this study was to evaluate the repeatability, precision and accuracy of the testing technology for measurement of milk urea nitrogen levels.

The second objective of this study was to evaluate the effect of cow factors on MUN. The dataset consisted of 68,158 observations for 10,688 lactating Holstein cows in 177 herds that participated in the Atlantic Dairy Livestock Improvement Corporation (ADLIC) production recording service.

The third objective of this study was to determine seasonal variation in bulk tank milk urea nitrogen (BTMUN) concentration in PEI dairy herds, and to evaluate the relationship between BTMUN and the weighted herd average of individual cow MUN levels (WHMUN). (Abstract shortened by UMI.).