Temporary social isolation is a common practice on dairy farms e.g. during insemination, although it is known to be highly stressful for cattle. Mimicking the presence of a conspecific (e.g. visual, tactile) can ameliorate an individual's stress response. This study examined if stress during social isolation can be reduced by providing both visual (mirror) and/or tactile (automated cow brush) stimuli.
In this experiment eighteen cows were socially isolated in four test sessions of 30 min each with the presence of either i) no stimuli (control), ii) a mirror, iii) an automated brush or iv) both. Mean heart rate, heart rate variability (RMSSD), locomotion, exploration, self-grooming, standing near the exit, rumination, and five different ear postures (i.e. upright, forwards, downwards, backwards, asymmetric) were measured. Behavioural and physiological parameters were analysed during 0-5 min, 10-15 min, and 20-25 min of isolation. Additionally, ear postures, heart rate, and RMSSD were analysed 1 min before, during, and 1 min after interactions with the brush or mirror.
Mean heart rate, the proportion of cows in locomotion, self-grooming, standing near the exit, exploring, and the proportion of ears backwards decreased over time during the 30 min isolation across conditions. In comparison with control (no stimuli), RMSSD was significantly increased and mean heart rate was significantly decreased in isolation conditions with either a brush or mirror present. In these latter conditions, the proportion of cows in locomotion and the time spent with ears upright were significantly lower compared to control. With both the brush and mirror present during isolation, the time spent with ears upright was decreased and the time spent with ears forward was increased relative to control. No clear effects of the actual interaction of cows with either a brush or mirror on ear postures, heart rate or RMSSD were found.
These results suggest that the mere presence of these stimuli represented a form of environmental enrichment that helped the animal to cope with the stress of social isolation, regardless of the actual interaction with them. Overall, stress levels in cows seemed slightly reduced when either a brush or mirror was present during social isolation.
Student: ML Wenker
Supervisor: dr ir K van Reenen