Quality monitoring of milk recording

Repeated tests are a labour intensive part of the quality control system of milk recording in The Netherlands. Therefore, parameters based on data from test days and milk deliveries to the dairy factory which are suitable to detect outlying tests are developed. By means of monitoring, the quality system will become more efficient and less expensive. A suitable parameter is the difference between milk/cow/minute by day and by night (DeltaMCM). It indicates tests which concern a period of more than 24 hours. DeltaMCM can be predicted on the basis of month of testing, average 305 day milk yield and interval by night between the milkings. Tests with an observed DeltaMCM deviating more than two standard deviations from the predicted DeltaMCM can be flagged. As the repeatability of DeltaMCM is low (0.33), more tests should be considered to assess the quality of collected test day data of a herd. Further tests with a relative difference between daily milk yield according to milk recording and according to the delivery to the dairy factory of lower than -8.17 percent or higher than 13.2 percent can be flagged. The difference between milk recording and dairy delivery should not be lower than -0.21 and larger than 0.23 for fat percentage and lower than -0.06 and larger than 0.09 for protein percentage.