Activity level of grazing dairy cows, as a criterion for grazing management in pasture-based dairy production systems

Various studies have evaluated the use of electronic devices to automatically record the grazing behavior of dairy cows. Linking individual grazing behavior of dairy cows with the modifications in grazing behavior across the grazing session through the use of automatically registered indicators, would allow the development of decision-making tools in grazing management. The objective of the present study was to evaluate the use of the activity level (AL) recorded with an accelerometer during the grazing-down process of a pasture grazed by dairy cows as a possible criterion for decision-making related to grazing management. A completely randomized design was used to evaluate the AL of dairy cows in two contrasting pasturebased dairy production systems: A pasture-based system with high concentrate supplementation level and high herbage mass (HM), using high-yielding dairy cows (GRAZSUP), and a pasture-based system with minimal concentrate supplementation level and medium HM, using Holstein New Zealand strain (GRAZ). Pre-grazing HM was higher in GRAZSUP than in GRAZ (+750 kg DM ha-1), while forage removed was higher in GRAZ than in GRAZSUP (+1.9 kg DM cow-1 d-1). Although the production system influenced the characteristics of the pasture and the ingestive behavior of the dairy cows, when AL was evaluated as the proportion of the initial AL recorded at a time-point of the grazing-down process, there were no differences in each of the times evaluated. In conclusion, AL of grazing dairy cows was significantly affected during the grazing-down process, reflecting the modifications in grazing behavior across grazing session.