The research has been published in the Nature journal Scientific Reports.

In humans, negative moods are linked to pessimistic judgements about ambiguous stimuli, e.g., depression and anxiety sufferers tend to expect fewer positive outcomes in life. By contrast, happy emotions and moods are linked to more optimistic judgements.

This study is the first of its kind to investigate whether dairy cows also have this judgement bias, and whether optimistic judgements can be used as an indicator of psychological wellbeing, which is important for animal welfare.

Dr. Gareth Arnott, Senior Lecturer in Animal Behaviour and Welfare at Queen’s University and principal investigator on the research, explains: “Animal welfare scientists and dairy consumers have long been concerned that depriving dairy cattle of pasture access harms their welfare. Pasture access can promote natural behaviour, improve cows’ health, and cows given the choice spend most of their time outside. However, the effects of pasture access on dairy cows’ psychological wellbeing have been poorly understood – that is what our judgement bias study intended to measure.”

To conduct their study the researchers, as part of a collaboration with the Agri-Food and Biosciences Institute, gave 29 Holstein-Friesian dairy cows 18 days of overnight pasture access (which previous studies suggest improves wellbeing) and 18 days of full-time indoor housing (which previous studies suggest harms welfare).

Each cow was then trained to approach a food rewarded bucket location, but not approach another, unrewarded bucket location. After learning this task, to test judgement bias, the researchers presented cows with buckets in between the trained locations. Approaching these intermediate buckets would reflect an expectation of reward under ambiguity – an “optimistic” judgement bias, suggesting positive emotional states. The researchers found cows kept indoors full-time were faster to approach the known rewarded bucket location.

Andrew Crump, a postdoctoral researcher from the School of Biological Sciences at Queen’s and lead author of the paper, said: “Increased reward anticipation suggests that an animal has fewer rewards in its life, so our results indicate that pasture is a more rewarding environment for dairy cows, which may induce more positive emotional wellbeing than full-time housing.

“Britain and Ireland have mostly resisted the trend towards housing dairy cows indoors full-time. We hope that our research encourages farmers, retailers, government and consumers that pasture access is important for cow welfare, and should be protected. In countries where full-time housing is common, we hope that ours and other welfare studies challenge this trend.”

The Agri-Food and Biosciences Institute (AFBI) Hillsborough hosted the study. This work was funded by Northern Ireland’s Department for the Economy, as well as a project that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme.

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