Effects of pulsation type (alternate and simultaneous) on mechanical milking of dairy goats (I) : A study in Alpine goats varying the system vacuum level

The aim of this study was to assess the effect of alternate and simultaneous pulsation on milking performance (milk yield, machine stripping milk, milking duration, and average milk flow rate) of Alpine goats milked at two different system vacuum levels (38 and 42 kPa). To this end, a field study was carried out in a commercial farm of Northern Italy. A pre-experimental period was carried out and 164 goats with a similar parturition date were selected and distributed into two similar subplots of 82 goats according to their values of milk yield and milking duration. The experiment lasted 24 d and was laid out as a split-plot design. Each treatment lasted 3 days. Once every combination (2 pulsation types x 2 vacuum levels) was tested (Experiment 1), the same experimental design was,repeated in reverse order (cross-over design) to control the effect of lactation progress on the results (Experiment 2). Milk traits regarding milking performance (milk yield, machine stripping milk, milking duration, and average milk flow rate) and variables related to vacuum level in the milking cluster (vacuum in the short milk tube and vacuum fluctuation in the short milk tube) were recorded during morning and afternoon milkings. Results showed that the use of alternate pulsation reduced the vacuum fluctuations and increased the average vacuum in the short milk tube. Moreover, when a higher system vacuum level (42 kPa) was set, the use of alternate pulsation reduced the milking duration. We concluded that the use of alternate pulsation offers some advantages compared to simultaneous pulsation in high milk flow conditions.