Individual Variability in Response to Social Stress in Dairy Heifers
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Received: 28 May 2020 / Revised: 4 August 2020 / Accepted: 10 August 2020 / Published: 18 August 2020
(This article belongs to the Section Cattle
Mixing unfamiliar animals (or regrouping) is a common practice on dairy farms. This disruption in the social organization typically results in increased agonistic interactions and changes in time feeding and resting. Our objective was to study if different individuals subjected to a similar regrouping event would display different levels of engagement in social interactions and avoidance of social contact, and if these differences were associated with other behavioral changes. A total of 30 heifers were regrouped. Agonistic behaviors initiated and received, and feeding, resting and standing time and synchronization were recorded. Agonistic interactions were most frequent in the first 6 h after regrouping, with most taking place in the alleyways. Some individuals showed higher levels of engagement in these interactions, and others seemed to avoid aggressive interactions, suggesting different strategies were used to cope with the social stress of regrouping. Heifers that showed a more engaged strategy spent more time feeding. Those that showed higher avoidance spent less time feeding, less time resting and were less synchronized with others in their feeding behavior. We conclude that dairy heifers display different responses to social stress, and that in the case of regrouping, a more engaged strategy is more successful.