Significance of Group Composition for the Welfare of Pastured Horses.
Authors: Sigurjónsdóttir Hrefna, Haraldsson Hans
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Group Composition and Social Welfare in Pastured Horses Herd dynamics profoundly influence equine welfare through their effects on aggression and social bonding opportunities, yet systematic data on how specific group compositions drive these interactions remain limited. Sigurjónsdóttir and Haraldsson analysed social interaction records from 426 Icelandic horses across 20 groups (minimum eight horses each), examining correlations between herd composition, management factors, and behavioural frequencies. Several patterns emerged with clear management implications: breeding groups with a single stallion exhibited notably low agonistic behaviour; aggression decreased when young foals were present and when group membership remained stable; conversely, unfamiliar yearlings introduced to peer groups showed elevated aggression levels, whilst allogrooming occurred most frequently in smaller, unstable groups and amongst horses with fewer established grooming partners. These findings underscore that age-sex composition and social stability are critical levers for reducing conflict and facilitating affiliative behaviours—suggesting that practitioners should prioritise gradual introductions of mixed-age groups and minimise mid-season membership changes where feasible, whilst recognising that single-stallion breeding groups may offer unexpected aggression-reduction benefits compared to bachelor or multi-stallion configurations.
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Practical Takeaways
- •Maintain stable group membership and avoid introducing unfamiliar yearlings to peer groups, as this significantly increases aggression and reduces welfare
- •Include young foals in breeding groups to naturally reduce agonistic interactions and improve overall herd dynamics
- •Design pasture groups with consideration to age/sex composition, as this fundamentally affects aggression levels and social bonding opportunities
Key Findings
- •Breeding groups with one stallion showed significantly low levels of agonistic behaviour compared to other group compositions
- •Horses in groups with young foals and stable group membership exhibited reduced aggression
- •Unfamiliar yearlings in peer groups displayed especially high aggression levels
- •Allogrooming frequency was highest in groups with young horses, unstable groups, and those with limited preferred partners