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Assessing mood changes and vulnerability to stressors in dairy cattle

University of British Columbia

Routine farm management can involve painful and stressful procedures that cause negative affective states and may have long-lasting consequences. Despite a growing interest in animal welfare and affective states, few studies have explored whether housing conditions and routine farm procedures induce long-lasting negative affective states such as negative mood. The first aim of this thesis was to develop methodologies to explore whether dairy cattle show evidence of negative mood in response to common stressful conditions. For this, I first used an adapted judgment bias test to assess changes in mood following hot-iron disbudding. My results suggested that calves experience anhedonia (i.e. the reduced ability to experience pleasure) after hot-iron disbudding. Thus, I designed tests aiming to assess whether calves display anhedonia-like responses after experiencing hot-iron disbudding, regrouping and post-partum stressors including cow-calf separation. My results showed that cattle display signs of negative mood (i.e. negative judgment bias and anhedonia) in response to stressful routine farm procedures. The second aim of this thesis was to explore why individuals show strong variation in how they cope with stressors. For instance, I explored whether individual variation in expectations would predict higher vulnerability to stressors. Negative expectations (i.e. pessimism) may lead to negative perceptions, stronger responses, poor coping strategies (avoidance-based coping strategies), and poor recovery from stressors. My results show that stable differences in pessimism exist in non-weaned dairy calves and that more pessimistic animals perceive and respond more negatively to stressors. I conclude that the study of mood-related changes and individual differences help better understand how living conditions affect farm animal welfare.

Text

2020-12-15

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/76805

Applied Animal Biology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/