Time budget differences of high- and low-social rank grazing dairy cows

Abstract

The aim was to compare the time budgets of high- and low-rank cows that were separated from their herd for grazing between milkings. Twelve cows with greater dominance indices (GR cows) and 12 with lower indices (LR cows) were selected from a herd of 107 Holstein cows. Each group of 12 cows was grazed in a half paddock of 1.5 ha, separated by an electric fence, from 0830 h to 1540 h over 5 days. The behaviours of these cows (grazing, ruminating, standing, lying or walking) were recorded using instantaneous sampling of individual cows within each group throughout the day. GR cows were observed grazing on fewer occasions and walking on fewer occasions (P = 0.0006 and P < 0.0001, respectively) than LR cows, but ruminated more (P < 0.0001). Thus the time budget of high- and low-ranked grazing dairy cows differed even when they grazed separately.