Comparison of 2 systems of pasture allocation on milking intervals and total daily milk yield of dairy cows in a pasture-based automatic milking system

Cows milked in pasture-based automatic milking systems (AMS) have greater milking intervals than cows milked in indoor AMS. Long milking intervals greater than 16 h have a negative effect on milk yield and udder health. The impact of 2 systems of pasture allocation in AMS on milking interval and yield was investigated at the FutureDairy AMS research farm (Elizabeth Macarthur Agricultural Institute, New South Wales Department of Primary Industries, Camden, New South Wales, Australia) in late November to early December 2010. Two- (2WG) versus 3-way grazing (3WG) allocations per 24-h period were compared in a field study to test the hypothesis that an increase in the frequency of pasture allocation would reduce the milking interval and, therefore, increase milking frequency. The study involved the entire milking herd of 145 cows, with (mean ± SD) DIM = 121 ± 90 d, 7-d average milking frequency = 1.52 ± 0.41 milkings/cow per day, and 7-d average milk yield = 21.3 ± 7.6 kg/cow per day. Cows were milked using 2 DeLaval VMS milking units (DeLaval International AB, Tumba, Sweden). Cows in the 3WG treatment had 31% reduced milking interval, 40% greater milking frequency, and 20% greater daily milk production compared with 2WG. Increased milking frequency and milk production for 3WG was associated with greater utililization levels of the AMS milking units throughout the day. These results support the recommendation that, wherever possible, farmers installing AMS should incorporate sufficient infrastructure to accommodate 3WG, which provides additional flexibility with managing extremely long (and short) milking intervals.