Analysis of results from 21 years of milking system inspections in Japanese dairy farms.

To prevent mastitis caused by inappropriate milking systems, inspection of the system, and maintenance of optimal function are crucial. This study aimed to clarify the problems with milking systems in Japan by analyzing the results of milking system inspections over the past 21 years. A total of 190 dairy farms (358 systems; 153 high-line systems, 205 low-line systems) were inspected for the checkpoints of problems originating from installation (PI) or problems originating from insufficient maintenance (PIM). Results were divided into initial and periodic inspections, then analyzed by year of inspection or years elapsed since equipment installation. With increasing years, inadequacy of milk piping and regulator maintenance tended to increase for high-line systems. On the other hand, defects in milking units tended to increase for low-line systems. This difference was attributed to the structures of these milking systems. The present study revealed potential problem areas in high- and low-line milking systems from recent years. To maintain normal functioning in milking systems, the frequency and content of inspections as currently being conducted need to be reviewed.