Cows' social networks: A Key Factor in Their Health and Well-Being

To date, our understanding of social connections and bonds among cows remains limited. However, these connections are believed to have a significant impact on the animals’ health and animal welfare. Researchers are studying allogrooming to understand these social bonds so they can better integrate them into dairy production management practices.   Dairy cows are farm animals that thrive within socially stable groups. Generally speaking, living in a herd provides protection against predators. On the other hand, life in a large herd involves competition for resources and a need for social organization to maintain a certain level of stability within the group. The social environment is critical to the health and animal welfare of the animals. Understanding the complexity of relationships among cows can help develop herd management practices that are better aligned with cows’ social behavior. In fact, to facilitate management in modern dairy production systems, herds of dairy cows are generally divided into several groups based on their stage of lactation and, consequently, their nutritional needs. Essentially, depending on their physiological and production status, each cow is moved to a new area where she is housed with different herdmates and subjected to the appropriate management routines. As a result, with each change, cows must recover from the disruption of their previous social bonds and establish new ones in order to adapt to their new social environment. The negative impact of this regrouping practice on behavior, animal welfare, and productivity has been well documented. Several studies highlight an increase in agonistic behaviors, as well as a decrease in affiliative interactions, rest periods, feeding and rumination times, and milk production. Despite the significant impact on the animals, our understanding of social interactions among cattle remains, for the time being, limited to spatial proximity. Studying contact behaviors between individuals could provide more detailed information, such as the type of interaction and its directionality (who initiates the interaction and who receives it). To better characterize cows’ social behaviors and understand their ability to adapt to a changing social environment, veterinary researchers from Chile and the United States have therefore focused on allogrooming, also known as social grooming. In addition to its hygienic and pleasurable benefits, this established behavior maintains and strengthens interindividual and preferential bonds. It improves group cohesion, maintains social stability, reduces tension, and has calming effects. The scientists studied the dynamics of relationships among dairy cows in early lactation using allogrooming as an indicator and explored the underlying processes and individual attributes—such as age, social rank, and reproductive status, that might shape the cows’ social and contact networks. Cows thus tend to groom individuals who had previously groomed them, which suggests a cooperative principle. Furthermore, cows that groom themselves more actively do not appear to have a preference for specific individuals in the herd and, in turn, tend to be groomed by fewer cows over time. Older cows groom more cows than younger ones, indicating that allogrooming may be linked to seniority. And cows primarily groom individuals of similar age, suggesting that familiarity and growing up together may enhance social grooming. Over time, cows with higher social rank are groomed by fewer cows, and individuals recently reintroduced into the group groom more of their peers. Studying social network dynamics can help us better understand the complexity and nonlinearity of relationships among cows. These findings could complement and strengthen the design of management practices, improving them so that they better align with the natural behavior of cows.