Effects of milkline vacuum, pulsator airline vacuum, and cluster weight on milk yield, teat condition, and udder health.

The influence of milkline vacuum, pulsator airline vacuum, and cluster weight on complete lactation milk yield performance, teat condition, and udder health were studied in 241 cows by using three separate factorial experiments. The first experiment had milkline vacuum set at 38 and 48 kPa, pulsator airline was vacuum was set at 0 and 8 kPa above milkline vacuum, and cluster weight was 1.6 and 2.3 kg. The second experiment had milkline vacuum set at 38 and 48 kPa and cluster weight was 1.6 and 2.3 kg. The third experiment had milkline vacuum set at 32 and 42 kPa and pulsator airline vacuum 0 and 8 kPa above milk line vacuum. The first two experiments were carried out with a high-level milking and the third with a low-level milking system. The average vacuums in the short milk tube during milking for low and high milkline vacuum in the high-level system were 26 and 33 kPa, and 30 and 39 kPa for the low-level milking system, respectively. Milking at low vacuum increased the machine-on time and frequency of liner slip, decreased milk flow rate, but had no influence on teat condition and udder health. The milk yield of high producing cows with long machine-on time was reduced by 5% when milked at a low vacuum. A higher pulsator airline vacuum than milkline vacuum had no influence on milking performance. The use of the light cluster reduced machine-on time. We recommend that mean vacuum in the short milk tube should not be lower than 32 kPa.