Cow traffic in an automatic milking rotary system : comparing single alley and open waiting area

Sammanfattning: In automatic milking systems it is of great importance that cows voluntarily enter the milking unit, negative experience of milking can influence motivation for entering the unit and in turn affect both production and health. Batch milking in an automatic milking rotary (AMRTM, DeLaval International AB, Tumba, Sweden) enables several cows to be milked at the same time. A holding area before the entrance to the rotary often supplements this system. Studies have shown if more time than 2.5 hours a day is put into the total milking procedure milk production may decrease, since the long time away from pens will affect the time put on feed intake and the time spent resting. The layout of the holding area might influence the cow traffic and the milking efficiency and for this reason, a single alley (SA) and a more traditional open waiting area (WA) were compared to estimate the effects on milking time and social interactions as well as labor time for herding cows into the AMR. A total of 138 lactating cows of Swedish Red and Swedish Holstein breeds were included in the study, and divided into two groups; the G1 group consisted of mostly primiparous cows and the G2 group of mostly multiparous cows. After cows were collected for milking, staff was not permitted to interact with cows for 40 minutes, unless downtime occurred in the AMR. Labor for herding cows after these 40 minutes was calculated. The treatments were applied for 14 days, and data was collected for the last 6 milkings of each treatment period that were successfully completed. Behavior data was analyzed for treatment differences using Student’s t-test in Excel and automatically collected data on milking times was analyzed using Proc Mixed in SAS. The results showed a higher frequency of interactions in SA compared to WA (p < 0.01). For the treatment WA, G1 performed overall more interactions compared to G2 (p < 0.05). No difference between treatments was found for time required for the overall milking time, although differences were found between groups. A higher proportion of cows in G1 entered the AMR voluntarily, and waiting time was shorter for G1 (p < 0.01). When staff interacted with cows, less time was spent on herding the G2 group (p < 0.05). In contrary, less time in total was spent on the milking for the G1 group (p < 0.05). Generally, total time away from pens was long (> 75 minutes), which probably would affect cows production and health. The two treatments differed with regards to social interactions, but it cannot be determined if interactions in the restricted area correspond to the whole holding area. Therefore, more research should be conducted to evaluate if any of these two systems affect the prevalence of interactions. 2