EFFECT OF VACUUM AND MILKING MACHINE LINERS ON LINER SLIP

The effect of milking machine liners and operating vacuum of 50 versus 44 or 42 kPa upon the frequency of liner slips, major vacuum fluctuations, manual machine adjustments, unit fall offs, milk yield, and milking time were enumerated in The Pennsylvania State University dairy herd of approximately 160 milking cows. Two separate trials were conducted using two liner types at two vacuum settings for each trial. Data were utilized from four milkings with each combination of liner and vacuum. Liner type, vacuum, and the interaction of liner type with vacuum were associated with the frequency of liner slips and major vacuum fluctuations in both trials. Liner slips, major vacuum fluctuations, manual adjustments, unit fall offs, and milking time increased at a lower operating vacuum. More slips occurred during the a.m. than during the p.m. milkings. Results indicate that machine liner design and construction and operating vacuum influence the occurrence of liner slips. Optimization of vacuum setting and liner design could improve machine milking.