The effects of social dominance on dairy cows' (crossbred Holstein-Friesian; n = 30) visits to an automatic milking system (AMS) and their daily activity pattern was studied. Cows were fed on concentrate and milked in the AMS, which consisted of 2 selection units (sending cows for milking or back to the herd) and one milking unit. In phase 1, cows were milked 3-times daily. Initially they received 100 g of concentrate when they visited a selection unit (A1). Later, they were dispensed concentrate in the selection unit only if they were still owed some of their daily ration (A2). In phase 2, 10 cows were milked 5-times and 19 cows 3-times daily. Concentrate was dispensed in time-windows corresponding with the planned milking frequencies. Cows which visited the AMS less than they should were stimulated to pay more visits by being rewarded with 100 g of concentrate even if they had already consumed their concentrate allowance for that particular feeding period. Social dominance was expressed as the dominance value (DV) of each cow (the relative number of subordinate cows). Daily concentrate allowance was incorporated into the statistical model. DV was positively correlated with the number of days of lactation in phase 1 and 2 (P<0.01) and to the milking interval in phase 2 (P<0.01). These variables were not incorporated into the statistical model because they were also correlated with daily concentrate allowance. The number of visits to the AMS and the total time spent lying or feeding each day were not correlated with DV. Timing of visits to the AMS and to the feeding gate were correlated with DV. In A2 and B, cows with higher DV paid more visits to the AMS between 12.00 and 18.00 h (P<0.05). In B, these cows paid fewer visits to the feeding gate (P<0.05) between 0.00 and 6.00 h. Waiting in front of the AMS was affected by DV: cows with higher DV could enter the AMS more often without waiting in A1 (P<0.05) and spent less time in the waiting area in B (P<0.01). It was concluded that introduction of fully automatic milking systems will trigger effects of social dominance, especially concerning the timing of visits to the AMS and the feeding gate and the waiting of low-ranking cows in front of the AMS.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||DLO Institute of Agricultural and Environmental Engineering (IMAG-DLO), P.O. Box 43, NL-6700, AA Wageningen, Netherlands.|
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