Field validation of a milk line sampling device for monitoring milk quality and udder health

The objective of this study was to investigate the ability of a milk line sampling device to obtain a representative sample by comparing SCC and bacterial culture results 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 herds. Concordance correlation coefficients showed a high level of agreement between the two sample types, with values ranging between 0.74 and 0.99 for all parameters and bacterial species measured. ANOVA showed that SCC and bacterial culture results for Streptococcus agalactiae, Staphylococcus aureus, Streptococcus non-agalactiae, Coliforms, and coagulase-negative staphylococci were neither numerically or statistically different between milk line and bulk tank samples. KAPPA analysis showed that overall agreement beyond chance between milk line and bulk tank samples in determining whether a herd was positive or negative for either Strep. agalactiae or Staph. aureus were 100 and 75%, respectively. While further research is needed to fully assess the utility of this tool for the purpose of bacterial culture, the results of this study suggest that the strategy of milk line sampling is a very promising monitoring tool. This sampling strategy should provide producers with inexpensive and timely information that will help to improve programs for monitoring milk quality and udder health in commercial dairy herds.