SOME calves are inherently optimistic or pessimistic and recognising these individual personality differences is important to ensure animals are treated well, Canadian researchers say.
University of British Columbia professor Marina von Keyserlingk, who led the research team, set up an experiment involving 22 calves to gauge optimism and pessimism.
“Sometimes we are tempted to see only the herd, even though this herd consists of different individuals who cope differently with stressful events,” von Keyserlingk says. “It’s important to consider the individual’s perspective, because even if conditions are good, on average, some animals may still suffer.”
Before they started the experiment, the team trained the calves to understand which of their choices would lead to a reward. Each calf entered a small pen and found a wall with five holes arranged in a horizontal line, two-and-a-half feet apart.
The hole at one end contained milk from a bottle, while the hole at the opposite end contained only an empty bottle and delivered a puff of air in calves’ faces. The calves learned quickly which side of the pen held the milk reward.
Researchers presented bottles in one of the three intermediate holes, so that calves couldn’t be sure if they would be rewarded with milk.
They predicted the most optimistic calves would approach the bottle even if it were positioned close to the location that earlier gave them an empty bottle and puff of air. In contrast, the most pessimistic calves would avoid approaching a bottle in the intermediate holes, even if it were close to the rewarded location.
The researchers say the calves varied in their responses, but individual calves remained consistent in their outlook and made similar choices three weeks apart. The conclusion was that pessimism was a consistent individual trait, not just the result of temporary moods or emotions.