Behaviour and throughput of dairy cows when entering and exiting two types of parallel rotaries
Today a trend can be seen towards fewer dairy farms and increasing number of cows per farm. Larger farms set a higher demand of more labour efficient milking systems. The time to enter and exit milking rotary platforms is crucial to maintain a high cow throughput. This study is a project initiated by DeLaval in order to evaluate the cow throughput and cow behaviour during entry and exit in two types of parallel external rotaries with different bail designs. The two rotaries compared were DeLaval parallel rotary PR2100 and PR3100HD. The study included nine different farms located in Sweden, Denmark and Germany.
The cow throughput was significantly higher in the PR3100HD with 277.7 cows per h compared to the PR2100 with 196.9 cows per h. The individual cow exit time was significantly shorter in the PR3100HD with 13.3 s compared to 19.8 s in the PR2100. No significant difference could be found for cow entry time between the two rotary models and the average entry time was 5.1-5.4 s. When feeding in the rotary and cow locator in the bail was investigated these factors had no significant effect on cow entry time. In the PR3100HD the cows were pushed by other cows significantly more during entry compared to in the PR2100. The cows were backing into other cows significantly more and showed a tendency of standing still more at the exit in the PR2100, causing problems for the cow throughput. Other observed behaviours during entry and exit were not significantly different between the two rotary models. Direct observations indicated that the cow throughput could be improved by further development and adaptation of the layout in exit area and exit lane.