Cows licking cows: social dynamics of a happy herd

Gefore social distancing, when we saw our friends we might have shaken their hand, slapped them on the back, or even given them a hug. Cows, though, choose a more intimate route and lick each other on the face and neck to say hello. Now, new research from the Universidad Austral de Chile has used this licking behaviour to assess the hierarchical relationships between cows in a herd - as lead researcher Gustavo Monti told Eva Higginbotham...

Eva - To be completely honest, in these trying times, I can't really think of anything more relaxing than sitting in a field and watching a group of cows lick each other. And that's exactly what members of the research team did every day, several hours a day, for a month: noting down who licked who, who got the most licks, who got the least licks, and how this changed over time. But the question remains: why?

Gustavo - One of the motivations of this study has to do with one consequence, which is arising from the way that we are managing cows, let's say in the Western type of production especially. Our systems are very intensive nowadays. And as a part of the management, animals are grouped and regrouped very often for different purposes. This is a problem because to establish this hierarchy and this relationship for a group of cows takes some time. The problem is once they reach this equilibrium, or status of recognition, then because of the management, some of the cows - or even the leader - is removed from the group and then new cows or new animals come to this group. Therefore they have to reestablish all the process all over again. And this has happened several times within a year within a group, and within the life of the cows.

Eva - Previous studies have shown that the constant reshuffling of animals can make them stressed out, and farmers have known for a long time that stress can have a big effect on milk production. The researchers wanted to understand the effects of this reshuffling on the social dynamics of the herd, and realised that they could use licking events as a window into these social dynamics. So they observed the cows without interfering.

Gustavo——我们的老大哥,是吗?

Eva - And plugged the data into a computer to perform a modern technique called social network analysis, where each cow is represented by a node and they could scrutinise the complex web of relationships over time. Kind of like Facebook for cows.

Gustavo - It's the same technique that is used nowadays with big data. So when Facebook or whatever company wants to evaluate who are your relationships, with whom you are working, or with who are you in contact; it's the same sort of techniques that were used for our situation. One of the important findings of this study was that unexpectedly, dominant cows licked more than the younger cows in the group, and seems that this could explain that the leader in some way, is offering this as a sort of action to reward the low level animals to keep the cohesion. I think one important finding is that in social grooming in both ways, they can establish individual bonds between members of the group. And this also enhances the overall social cohesion of the herd.

Eva - They also found that cows that were new additions to a herd were licking more often, and hypothesised that maybe they were doing favours and trying to be friendly to get down with the new group. Interestingly, though, the cows that did the most licking received the least licks in return. This might be because licking another cow is something of an investment. And if you go around licking everybody, it might suggest that you're not going to invest in specific relationships, and so the other cow might not bother investing in you either. Overall, Gustavo and the rest of the team suggest that licking can be used as a positive marker for wellness within a herd. If there's lots of licking, things are stable and everyone is content with their friends. If there isn't, things are going wrong in the complex social and emotional relationships of the herd; and Gustavo argues that farmers should be mindful of this important aspect of cow's welfare when reshuffling the group.