February 28, 2014 | 1
My schoolteachers took effort to separate close friends when arranging their classroom seating charts. The idea was that we’d pay more attention to our lessons if we were distracted by our buddies. Dairy cattle also tend to be separated from each other, but that may actually put them at a disadvantage. Calves are separated from their mother and housed individually until they’ve been weaned from mom’s milk, around six to eight weeks of age. Dairy farmers do this because it seems easier to manage cows individually than in groups.
But scientific research has demonstrated that social housing early in life reduces the distress associated with weaning. That makes good intuitive sense: social species need social interaction not just to thrive, but possibly even just to survive. It isn’t just human children who suffer when raised in isolation. In the laboratory, animals like rats, which are social critters, perform more poorly on tests of cognitive development compared with others who are raised in tiny little rat families.
Animal welfare researcher Charlotte Gaillard of the University of British Columbia wondered whether, like rats, cows also benefit in terms of cognitive development from social housing early in life. After investigating the literature, she discovered that no study had ever directly assessed cognitive performance in juvenile dairy cattle as a function of social or isolated housing. Perhaps the dearth of research is because livestock are usually thought of primarily in functional terms as providers of milk or meat, leather or labor. Her research was published this week in PLoS ONE.
The experiments, all done on singly- or socially-housed calves aged between 4 and 8 weeks, were fairly straightforward. In one test, the cows were taught to associate either a black square or a white square with a food reward. Once they demonstrated that they had formed the association and reliably chose to feed from the correct feeder, the reward structure was swapped. If the white square was initially associated with the reward, now the black square was. How long would it take the cows to relearn the associations? This type of test measures a cognitive skill called “reversal learning.”
In a second test, cows were placed in a pen with an unfamiliar object, a plastic red bin. Researchers measured how willing the calves were to inspect and interact with the object, such as by sniffing, licking, or pushing it, and then how quickly they grew bored of it. Plastic red bins shouldn’t remain exciting for very long, after all. Even for a cow.
The results, like the tests, were also very straightforward. None of the calves had difficulty learning to associate a color with a reward in the first place. But that’s where the similarities ended. Calves who were housed in isolation had a much more difficult time with the reversal learning task than did their counterparts who were housed in groups. While the individually-housed calves did eventually succeed at the task, it took them on average six additional trials to reach the success criterion established by the researchers. Gaillard thinks that the social calves may have learned to be more behaviorally flexible. “Inflexibility in the individually-reared animals can be explained as the result of living in a more predictable environment; social contact introduces variability into the environment, and animals that are reared without this complexity may be less able to cope with it,” she says. By contextualizing her findings within other research, she hypothesizes that the isolated calves may actually have underdeveloped brain tissue in the prefrontal cortex compared with the social calves, or reduced interconnectedness between the prefrontal cortex and other areas of the brain.
The effects of differential housing were more stark when it came to the novel object task. Calves housed in pairs eventually grew bored with the red tub, while the calves housed alone never really got used to its presence. Gaillard isn’t sure just why the individually-housed calves never habituated to the novel object. Like the reversal learning task, it could be due to a cognitive deficit, perhaps with memory encoding. Differences in emotion processing would also explain it. The individually-housed calves could have had increased anxiety, reflecting a more fearful or uncertain attitude about the world. “Anxiety might delay habituation by preventing the calves from approaching and thus learning to recognize the novel object or by making them slower to consider it non-threatening,” Gaillard explains. It could also be that their sustained interest in the novel object reflects increased sensation-seeking, since living alone is rather boring if you’re a young cow.
Whether the differences in either task are ultimately assigned to cognitive deficits or to shortfalls in emotional control, it’s bad news for cows raised in isolation. The way we think about domestic livestock is slowly changing, and researchers and farmers alike are starting to realize that these animals not only have complex social lives and personalities, but that more enriched housing can also lead to improved quality of life not just for the animals but also for the farmers and technicians who care for them. Dairy cattle, for example, face many challenges in their day-to-day management. They have to adjust to changes in feeding environment, social regrouping, and must learn to interact with technological innovations like robotic milking machines or automated feeders. “Individuals that are more flexible might adapt more quickly to these changes,” Gaillard writes, “improving the lives of the animals and the farmers that work with them.”
In the end, cows are not simply machines that produce milk when you yank on them. Instead, they’re complicated animals with nuanced mental lives, subject to some of the same kinds of learning difficulties as human children. They do, however, produce milk when you yank on them. That part is true.
Gaillard C., Meagher R.K., von Keyserlingk M.A.G., & Weary D.M. (2014). Social Housing Improves Dairy Calves’ Performance in Two Cognitive Tests, PLoS ONE, 9 (2) e90205. DOI: 10.1371/journal.pone.0090205.g003
Header image: A calf in England, New Forest National Park via Wikimedia Commons/Jim Champion.
For more on cognition and behavior in domestic livestock:
Are Sheep Better at Botany Than the US Government?
Like the Honey Badger, Petting Zoo Animals Don’t Care
Secrets of the Universe: Past, Present, FutureX