WESTERN PRODUCER — Most farmers working daily with dairy or beef herds recognize personality traits in individual animals. That knowledge is helpful for herd management and it is also a key indicator linked to productivity, health and the welfare of those vulnerable to stress and at greater risk to sickness.
Recognizing the importance of personality profiles, researchers at the University of British Columbia undertook a long-term study of Holstein cows to define the importance of recognizing personality traits and understand why some animals are more challenged than others to cope with perceived stress. The study also revealed that, during puberty, there is a change in personality and a period of inconsistency. It is believed to be the first study of its kind in a farm animal species.
“The whole idea of studying personality traits for animal welfare is to detect which animals might be more vulnerable to stress,” said Professor Marina von Keyserlingk, Natural Sciences and Engineering Research Council of Canada (NSERC) Industrial Research Chair in dairy cattle welfare. “Knowledge about their individual personalities may enable us to understand better why some animals fail to cope under standard management practices and are more likely to become ill.”
She said that the time around calving is a prime example. At that time, many things are changing for the cows, including the food they get, unfamiliar pen-mates, learning how to be milked in the milking parlour, and all the physiological changes that come with having offspring.
“Dairy cows can get sick after calving and those animals that are more vulnerable to stress may be more vulnerable to infectious disease.”
The personalities of cows will define how they behave. Some are more confident in exploring their pasture for food while others are bold and will position themselves at the front of a herd while grazing or moving. As herd animals, cows are social and individual animals may have a particular friendship with another as a grazing partner. Young cows, developing their own confidence, may seek the company of a mature cow as a source of information such as where to feed or drink.
“This study identified two key personality traits that were shared across multiple time points: boldness and exploration,” said von Keyserlingk. “These traits have also been identified in other studies in dairy cattle. In one of our studies, we were interested in determining whether calves that had been identified as having a fearful or pessimistic personality early in life were more susceptible to certain situations compared to other calves that were not as fearful.”
Two groups of calves were studied at the university’s research farm. Group 1 included 33 female calves that were monitored from pre-weaning to first lactation. Group 2 included 32 female calves studied over the same duration. A sub-sample of male calves were studied during the early rearing period to post-weaning. One of the studies looked at the impact of transportation and how different personalities coped with the 10-minute experience being moved from one barn to another at the research farm.
“We measured vocalizations as an indicator that they were in distress,” she said. “The more they vocalized during transport, the more stressed they were. We also measured eye temperature as it increases as a result of increased blood flow to the eyes when they feel threatened.”
The combination of these measurements allowed them to evaluate the stress response. As expected, the information about the fearfulness trait allowed them to predict how calves reacted to transportation. The work showed that the pessimism trait was a reliable predictor of which animals would be most stressed. The more pessimistic calves vocalized more often and had higher eye temperatures after transportation.
“We found that cattle were consistently bold or exploratory in the early rearing period, from birth to about three months of age,” she said. “During the later period of development, from about one year to 2.5 years of age, cattle also consistently showed these traits. However, the study showed that, during puberty, when calves reached sexual maturity, there appeared to be a change in personality. This means that dairy cattle show consistent personality as calves and adults, but with a period of inconsistency around puberty.”
Major changes in the body can contribute to this such as changing hormone profiles, growth rates, metabolism, or morphology. Changes in the dairy cow’s physical or social environment can also contribute to personality influences. Dairy cows are often mixed with new animals, placed in new pens, or have to learn to use new feeding equipment, adding to stress levels.
“These changes in personality around puberty are also seen in squid, fish, junglefowl, and mammals like hamsters and mice.”
She said that the work provides evidence that, despite all the cows being Holstein, all being born on the same farm, and all being offered similar diets and social environments, there was tremendous variation among the animals tested.
Personality and behaviour tests included exposure to novel environments such as an empty arena, an unfamiliar person at the test arena’s centre and unfamiliar objects placed at the arena’s centre. Tests were conducted over three consecutive days and the testing arena was visually isolated from the herd. The study contributed to further understanding the range of behaviour in farm animals and how individual animals differ.
“Different individuals reacted in different ways. Some calves and cows will immediately approach and investigate the object or human, or explore the new environment, while others will never touch the object or the person and stand still for the duration of the test. We interpreted the collection of these behaviours as reflecting two key personality traits: bold and exploratory.”
The research findings met with a lot of agreement among farmers.
“When we first presented the data at farmer meetings, I saw many of the participants in the audience nodding their head in agreement,” said von Keyserlingk. “I believe for many farmers our work is confirmation of what they already know – that not all cows behave the same way. However, what our work also provides is that personality differences can impact how the individual copes when exposed to stressful situations such as transport.”
The research was published in Royal Society Open Science.
