Field validation of a milk-line sampling device for monitoring milk component data

The objective of this study was to investigate the ability of a milk-line sampling device to obtain a representative sample under field conditions by comparing the milk component composition between milk-line and bulk-tank samples, for milk harvested from the same group of cows at the same milking. A total of 42 paired milk-line and bulk-tank samples were collected at separate milking events from 21 different dairy herds. Samples were analyzed for milk fat (%), true protein (%), and milk urea nitrogen (mg/dl). Concordance correlation coefficients showed a very high level of agreement between the two sample types, with values ranging between 0.82 and 0.95 for the components measured. ANOVA showed that milk component data derived from milk-line samples were neither statistically nor numerically different from milk component data derived from bulk-tank samples. The strategy of monitoring milk component data through milk line sampling should provide dairy producers with inexpensive, timely, and accurate information that will help to improve ongoing nutritional monitoring programs for individual groups of cows within the dairy herd.