Electric shocks during machine milking

When electrically driven milking machines were first introduced, one of the problems they presented was due to the leakage of electricity into the teat cups. Some early machines had a chain drive from the motor to the vacuum pump. These were particularly liable to carry a volltage on the milk pipe, and in many cases this could be eliminated by the use of an insulated V-belt drive. Despite improvements in machine and shed design, electrical voltages on milking machines continue. Phillips (1962) reported finding plant voltages from, 0 to 20, with the majority in the range 3 to 10 volts in the Waikato and Taranaki. A similar study carried out in New South Wales (Whittlestone and Harper, 1962) showed voltages ranging from 0 to 16. Earlier studies at the Ruakura Animal Research Station (Whittlestone, 1951) showed that electric shocks applied to a cow before milking will produce a substantial change in the nature of the milk ejection curve…