A simulation model of an automatic milking system applying different management strategies

A simulation model to test different management strategies for using robotic or fully automatic milking on dairy farms was constructed. An automatic milking system (AMS) is any system that allows dairy cows to be milked on demand with little or no human interaction. Typically, it consists of a selection system to identify the cow, a holding area, milking stalls served by a robot and an automatic concentrate feeder. It is likely that an AMS will be commercially available in the UK soon and it is therefore timely to consider the use of systems within farm practice. In the UK, most herds spend half the year grazing and otherwise housed indoors. It is unlikely that farmers would accept a change to a fully housed system. Thus, the benefits and drawbacks of an AMS for fully housed, zero-grazed and manually fetched (from fields) systems need to be examined. A three-phase discrete simulation model of an AMS has been developed. It has been used to study the performance of systems under a range of management options, including voluntary presentation, manual batch presentation and a mixture of the two, and to analyse the effect of herd size, milk yield and calving pattern. The results show that block calving systems need 20% larger milking capacity for the parlour than all-year calving, and that the difference in capacity of the robot between high and low yielding herds is small. Approximately, 30 cows can be milked by each milking stall for all-year calving herds, with a possible 100 milkings per day despite closure of the parlour for 6 h each day. The capacity of the milking parlour is not increased if more than four stalls are attached to each robot. (C) 1998 Silsoe Research Institute.