Effects of flow-responsive milking on milking performance of an automatic milking installation

The objective of this study was to compare a quarter-level vacuum-control system that maintains teat-end vacuum during milking to a similar system with conventional vacuum-control technology for which teat-end vacuum is reduced as milk flowrate increases. A study was performed on a pen of cows that had free access to one automatic milking system with conventional vacuum control and another automatic milking system with flow-responsive vacuum. The study ran for 111 d, during which time the pen contained between 120 and 128 cows that had free access to either milking station, producing a dataset with more than 32,000 milkings. The conventional control system maintained the receiver vacuum at 46 kPa, with a resulting vacuum drop at the teat end proportional to milk flowrate, while the flow-responsive treatment maintained a short-milk-tube vacuum at 45 kPa for the entire milking process. The milk removal rate was 12% greater for the flow-responsive system compared with the conventional vacuum system when measured over the milking station occupancy time and when measured by the milking time (first teat cup attached to last teat cup removed). The quarter-level milk removal rate was 16% higher for the flow-responsive treatment. The milk yield per milking compared with the expected milk yield, based on milk production rate and time since last milking, was 102 g higher at the udder level and 22 g higher at the quarter level in the flow-responsive system than in the conventional vacuum-control system, indicating more complete milking.