Effects of an extended c-phase on vacuum conditions in the milking cluster

•Two pulsation cycles differing in their closing phase durations were investigated.•Results showed decelerated closing of the liner might be more comfortable for cows.•Elongated c- and shortened d-phase showed a lower pressure sum.•Elongated c- and shortened d-phase showed lower air accelerations at the teat-end.•Elongated c- and shortened d-phase showed a higher maximum vacuum at the teat-end.

The objective of this study was to examine how a prolonged closing phase in the pulsation chamber cycle would affect vacuum conditions on the teat and liner movement. Wrong vacuum conditions and liner movements, controlled by pulsators, could cause discomfort on the teats and have negative effects on udder health. Therefore, 18 focal dairy cows were randomly subjected to two types of pulsation chamber cycles (treatments A and B) for 12 milkings in a low-line 2 × 3 auto tandem milking parlour. The treatments differed in the duration of closing and closed phases (c- and d-phases, respectively). In treatment A, the c-phase was 70 ms and the d-phase was 330 ms, whereas in treatment B, the c-phase lasted 130 ms and the d-phase 270 ms. Using a vacuum measuring device, measurement series with 5 s intervals were conducted during three phases of the milking process: the plateau phase, the decreasing phase, and the over-milking phase. Differences between the treatments were detected in the total pressure per cycle and maximum vacuum on the teat-end. Treatment B showed on average a 1 kPa s lower total pressure per cycle than treatment A, whereas values of maximum vacuum at the teat-end were on average 0.2 kPa higher in Treatment B than A. Further, differences could be detected between the three phases during the milking proceedings, showing that the observed parameters were related to the milk flow rate. The results indicate that treatment B might be gentler and more comfortable for dairy cows, which will be established next.