In pasture-based systems, cows may spend several hours away from the paddock and may also walk several kilometres to meet daily milking requirements; this could lead cows to experience time constraints for grazing, ruminating and lying time in the paddock. This study investigated how walking distance and time spent away from the paddock affected daily behavioural patterns (i.e., grazing, ruminating and lying time) and milk yield. Dairy cows were managed in three rotationally grazed groups (n = 29 cows each) on the same farm and milked twice daily. A triaxial ear tag accelerometer on each cow recorded daily duration of grazing and ruminating, and a leg-based accelerometer recorded the daily lying time, for 13 days. GPS collars on four cows per group recorded the daily walking distance and total time away from the paddock for the group. A mixed repeated measures model tested how time off-paddock and walking distance affected the daily behavioural patterns; age, breed, milk yield and maximum ambient temperature were used as covariates with group as the observational unit. A second similar model tested how these factors affected milk yield. Walking distance and time spent away from the paddock were not correlated. When daily walking distance increased (to a maximum of 4 km/d), cows spent more time grazing and less time ruminating, but lying time was not affected. This result may, in part, be related to the greater energy expenditure demands for walking longer distances and milk production. When time away from the paddock increased (to a maximum of 4 h/d), cows spent less time lying, but grazing and ruminating times were not affected. Milk yield was not affected by walking distance, but one of the groups experienced a lower milk yield when time away from the paddock was increased. This result suggests that, for some cows, lying times may be shorter when experiencing a longer time away from the paddock, which may also affect milk yield. Overall, this study indicates that paddock behaviours are associated with walking distance to the milking parlour and time spent away from the paddock. Efforts to reduce walking distance and time spent away from the paddock are likely to provide cows with greater opportunity to engage in daily behaviours in the paddock that meet their needs and maintain their milk yield.
The effects of milking frequency in early lactation on milk yield, mammary cell turnover, and secretory activity in grazing dairy cows