Ranch horses want to do what most people would prefer after a solid day’s work — have a decent rest, according to researchers.
Pedro Henrique Esteves Trindade and his colleagues set out in a study to learn about the effects that work had on the body language of ranch horses in Brazil.
The country is home to about 5 million horses, of which 72% are based on beef cattle farms.
They are used mainly for cattle driving and for moving around the farm to check on animals, pastures, fences and water troughs.
Horses have been used for ranch work in Brazil since the 16th century. The possibility of replacing them with machines is often considered infeasible, due to economic or technical reasons.
The study team, writing in the open-access journal PLOS ONE, said that although ranch horses have an important role in Brazilian beef farms, almost nothing is known about their welfare.
They noted that while the response of horses to exercise is often monitored using physiological variables, physical and mental states can also be expressed through body language.
The study team used 14 crossbred ranch horses, comprising 13 geldings and one mare, from two farms for their research.
Ten of the horses worked a half-day, always in the morning; and the other four worked a full day — mornings and afternoons.
They were each assessed for seven non-continuous days during summer before and after their workday, recording their body language, as well as physiological and workload variables. Blood samples were taken for analysis. GPS was used to monitor the distances they covered, and heart rates were recorded.
The researchers wanted to find out if facial expressions and other behavioural variables changed in the horses after routine workdays, and to investigate if these changes can be used as indicators of physical tiredness.
On average, the horses had a work duration of about four hours, with some on the go for more than six hours. They covered an average distance of 18.7km, with some covering more than 20km in a day.
Their average speed was 5.4kmh.
The average heart rate was 91, with the average maximum heart rate across the horses being 146.
Results showed that, after a workday, the horses increased the frequency/duration of body language indicative of resting. They also devoted less energy toward avoiding flies.
Three variables of facial expressions — the duration of ears forward and nostril lift, and frequency of eye white showing — decreased after their workday, as did five variables of other behaviours (frequencies of skin movements back and front, touch, head-turning, and duration of head-turning).
The duration and frequency of eyes being partially closed, the score of tension in the muzzle, and frequencies of three legs supporting the body and weight-shifting between forelegs increased after the workday.
Most of the physiological responses — respiratory rate, cortisol, creatine kinase and lactate concentrations — increased as a result of a workday.
“We identified some specific body language changes indicative of an increase in resting, a decrease in attention to the surroundings and fewer movements to avoid flies after a workday that, from our perspective, have potential to be used to assess physical tiredness in horses,” they said.
The study team noted that some of the behaviours can be seen when horses are in pain. That led them to suggest that some ranch horses were probably experiencing a combination of tiredness and slight soreness.
“Of particular interest, because of the ease with which it can be assessed on the farm and generalized to other situations, we suggest that the frequency of shifting weight between the forelegs has potential to be used as an indicator of physical tiredness in horses.”
It was strongly associated with the workload performed.
This, they said, must be confirmed by further studies.
“The results can also be used in the development of tools to improve the welfare of ranch horses as well as horses used in other activities, although more research is needed to validate this assumption.”
The researchers stressed that the use of body language categories as indicators of physical tiredness is not necessarily clear cut, since some of them can also be displayed by horses when experiencing very different states.
“For example, eye partially closed can be observed when horses rest, or when they experience pain after castration and acute colic surgeries, or even during competition.
“In summary,” they continued, “we suggest that it is most realistic to assume that the changes observed in the body language and physiological variables reflect that some horses were tired or very tired, but without any of the deleterious consequences of physical activity.
“Nevertheless, the ranch horses were apparently experiencing a combined state of post-aerobic effort and slight soreness after a working day.”
The full study team comprised Trindade, Guilherme de Camargo Ferraz, and Mateus José Rodrigues Paranhos da Costa, who are with São Paulo State University; and Elke Hartmann, Linda Keeling and Pia Haubro Andersen, with the Swedish University of Agricultural Sciences.
Trindade PHE, Hartmann E, Keeling LJ, Andersen PH, Ferraz GdC, Paranhos da Costa MJR (2020) Effect of work on body language of ranch horses in Brazil. PLoS ONE 15(1): e0228130. https://doi.org/10.1371/journal.pone.0228130