Body Condition Score correlates with dominance in pasture kept horses

29 Mar 2015

Researchers at the University of Bristol conducted a study of 194 pasture kept horses living in groups, and found that body condition score correlated significantly with herd hierarchy. Dominant horses were more likely to be obese compared to horses lower down in the pecking order. The researchers are unsure if this is a cause or effect, and further research needs to be conducted in this area; perhaps horses are more likely to be dominant when they have a better physical condition or perhaps they have a better physical condition because they are dominant. However, the research does highlight that more dominant animals are likely to be at higher risk of obesity and, therefore, obesity-related diseases such as laminitis. Horses such as these should have their weight monitored closely.

The researchers also found that smaller equines kept at pasture were more likely to have a higher body condition score than larger equines, agreeing with previous research and the stereotype that ponies are more prone to obesity and thus laminitis than larger animals.

The study was conducted at a time when grass density was low, just before the growth of spring grass had begun. Horses were firstly given a body condition score in the paddock. A dominance test was then conducted where piles of feed were spaced out and given to each horse, and the group was filmed until all of the feed had been eaten. During feeding, dominant behaviours were noted and behaviour that made another horse leave his or her feed was recorded, such as a bite or kick threat. A dominance score was then calculated and averaged out by the number of horses in the group.

Age did not correlate with body condition score, although age was found to have a relationship to dominance level such that middle-aged horses were found to be the most dominant.

The study revealed that younger animals were the most interactive with other equines. Dominant interactions between animals of the same age and height also tended to be more numerous, indicating that perhaps paddocking animals of different ages and sizes together is less likely to lead to injury. A previous study has found that mares were more likely to have friendly interactions with other mares who were a greater age difference from themselves.

Sex did not correlate with body condition score or dominance, with mares and geldings showing no significant differences in dominance levels. No stallions were used in the study.

This study supports hypotheses made by past researchers that groups of herd animals with greater physical variation have greater social harmony. Situations where this theory is applicable, are studs where animals of similar age and breed are often turned out. This study agrees with the practice of using an older “nanny” animals to break up herds of younger yearlings or weanlings turned out to mature, to help keep the peace.

 

Reference

Giles, S. L., Nicol, C. J., Harris, P. A., & Rands, S. A. (2015). Dominance rank is associated with body condition in outdoor-living domestic horses (Equus caballus). Applied Animal Behaviour Science.