Voluntary cow traffic and behaviour in the premilking yard of a pasture-based automatic milking system with a feed supplementation regime

Operating a voluntary, pasture-based automatic milking system presents challenges not encountered in indoor-housed systems, including long walking distances, exposure to climatic changes and large herd sizes. Feed incentives can be used to encourage voluntary cow traffic in both pasture and indoor systems, and may be particularly useful at the dairy where the risk of congestion is high if cows do not progress through the system promptly. The present study investigated the effect of a supplementary feeding regime on voluntary cow traffic and cow behaviour in the premilking yard of a pasture-based automatic milking system. Cows were strategically granted access to supplementary feed given at the dairy either before (PRE) or after (POST) milking. The mean voluntary waiting time, being the length of time it took for a cow to present for milking when given uninhibited access to the robotic unit, was 21% shorter for cows in the POST treatment than for those in the PRE treatment (60.2±4.6 and 76.1±6.0min respectively). Additionally, a greater proportion of hourly voluntary milkings throughout the day and early night were associated with cows in the POST treatment. On average, high yielding cows and cows in their first or fourth lactation spent less time in the premilking yard. Voluntary waiting time increased as queue length increased, with cows waiting (on average) less than 53min when there were fewer than 20 cows (equivalently, 14 cows/100m2) in the premilking yard and more than 90min when queue length exceeded 40 cows (equivalently, 28 cows/100m2). Cows in the POST treatment were more likely to be observed facing towards the robot and located closer to the robot entrance, and were less likely to be observed lying down in the premilking yard. Results indicated that offering supplementary feed directly following milking favourably altered cow behaviour and successfully reduced the voluntary waiting time of cows in the premilking yard, with the potential to reduce congestion in the dairy facility, as well as improve cow health and system performance.