Seeking the best horse groups

It is best for horses to be kept in groups. Scientists are now studying more precisely how the groups should be composed.



Horses in groups always find a leader and a rank. Scientists are investigating the effects of different types of group compositions on the well-being of horses. Photo: Janne Hansen

There is general agreement that horses thrive best when kept in groups. The question is what is the best way to do it? Should horses in a group have the same age and sex or should there be a mix of age groups and/or sexes?

Under practical conditions horses are often moved many times in their lifetime, thus experiencing repeated group changes. A group of horses will always seek to find a leader and a rank. The question is how this can be done without too many hitches.

"Perhaps they would be better at handling new group compositions if they experience being moved from a young age. Our theory is that the frequent moves would develop the social skills required for stable and homogenous groups",  says scientist Eva Søndergaard, Department of Animal Health, Welfare and Nutrition at the Faculty of Agricultural Sciences, Aarhus University. She is involved in several research projects regarding horses in groups and their behaviour and welfare.

In one of the studies the dynamics will be created by changing horses in half of the groups every week during the study period. The scientists will watch the horses' behaviour closely. They will observe whether aggressive behaviour, such as kicking and biting, towards new horses is mitigated in horses that are used to meeting new horses and if the behaviour in the groups depends on the group's stability.

Horse owners often put their horses in homogenous groups because it eases feeding. However, it is not certain that this arrangement is best with regard to horse behaviour. In a natural environment a group of horses normally consists of animals of different ages, sexes and life experience.

"When it comes to social animals, you cannot have a group without rank. Not everyone is equal",  Eva Søndergaard points out.

"Our hypothesis is that it is better when the composition of the group is heterogeneous. The rank can then be quite harmonious, depending on the leader",  she says.

The scientists will compare homogenous groups of horses with groups of young horses that have "mentor" horses among them. The mixed groups will consist of horses aged from one to three years and an older horse, that can take on the role as a mentor. The older horse will be at least two years older than the eldest of the young horses.

With these studies the scientists want to investigate how the horses act within the group and how it affects their later behaviour with regard to, for example, handling new challenges, learning and interactions with other horses.

"When we have more knowledge about group dynamics and group composition we will be better equipped to advise horse owners, advisors and veterinarians about the best ways to keep horses in groups",  says Eva Søndergaard.

The project is part of a large, Nordic project. The ultimate goal of the whole project is to identify general, basic principles and practical strategies regarding group housing of horses so that horse welfare is optimized and there is minimum risk for people.