Shade use by small groups of domestic horses in a hot, sunny environment.

This research investigates shade use and its effects on behavioural and physiological responses of small groups of horses, comparing instances where they have access to shade to where they do not. The findings suggest that horses utilize available shade and exhibit behavioural changes when access is denied, with no noticeable differences in physiological responses. The study will aid in developing future best management practices for horses in hot, sunny environments.

Overview of the Study

• The study was conducted to examine the use of shade by small groups of domestic horses and its impact on their behavioural and physiological responses. The horses were managed in outside pens or pastures, a common method of housing in the U.S.
• The research was carried out based on three trials with four groups of three horses each. Within each trial, the groups were randomized into two different treatments – with access to shade (SH) and without access to shade (SUN) for five days each in a crossover design.
• The climate during the study was monitored using automated sensors capturing weather factors round the clock. The average afternoon temperature was 31.0°C and the relative humidity level was 32%.

Methodology

• Three specific physiological measures were recorded daily at 1000, 1330, and 1900 hours: rectal temperature, respiration rate, and skin temperature.
• On the first and fifth days of the trial, venous blood samples were taken from the horses to determine serum cortisol levels, the neutrophil:lymphocyte ratio, and hematocrit (the proportion of total blood volume that is occupied by red blood cells).
• Behaviours such as the presence in shade, standing near or away from water, locomotion, foraging, and insect avoidance were observed at five-min intervals from 1400 to 1900 hours daily. These observations allowed the researchers to compare the behaviour of horses in the SH treatment with those in the SUN treatment.

Results and Conclusion

• The horses in the shaded conditions utilized the shade in 7.1% of the observations between 1400 and 1900 hours and showed varying behaviors compared to those under the sunny conditions. The real differences manifested in terms of their proximity to water locations and foraging activities. Horses with access to shade foraged more and stayed less near the water troughs than those without.
• The research found no significant differences in terms of physiological responses such as body temperature, breathing rate, and skin temperature, or in blood parameters between the horses with or without access to shade.
• In summary, the provision of shade has appreciable effects on the behavioural tendencies of horses and should be considered when drafting future guidelines for maintaining horses, particularly in hot and sunny climates.