Horses' Shade Preferences Evaluated
by Michelle N. Anderson, TheHorse.com Digital Editor
Date Posted: 10/29/2013 8:00:00 AM
Last Updated: 10/29/2013 8:00:11 AM

The benefit of horse housing might be obvious during cold winter months, but what about during sun-filled summer days?

Researchers at the University Of California, Davis (UC Davis), College of Veterinary Medicine and School of Animal Science worked together to execute several studies to investigate. Researcher Kathryn Holcomb, PhD, presented the results of two studies at the 9th Annual International Society for Equitation Science, held July 18-20 at the University of Delaware in Newark.

“Research shows that shade benefits livestock, leading to increased weight gain and milk production,” Holcomb said, but existing research about horse housing and weather primarily focuses on winter conditions. For the two UC Davis studies, researchers chose to look at climate conditions more common in California—sunshine and heat.

Both shade-related studies measured physiological and behavioral changes in horses, as well as environmental data.

Physiological measurements included:

  • Rectal temperature (RT);
  • Respiration rate (RR);
  • Skin temperature (SK); and
  • Water consumption.

Behavioral measurements included:

  • Foraging;
  • Locomotion; and
  • Proximity to water.

Environmental and weather data included:

  • Ambient temperature;
  • Relative humidity;
  • Black globe temperature, which measures the combined effect of ambient temperature and solar radiation;
  • Soil temperature; and
  • Solar radiation, which can be thought of as measuring the intensity of the sun, Holcomb said.

Twelve adult horses were housed individually for five days in either completely shaded pens (above) or completely unshaded pens (below), and then traded places for five days to serve as their own controls.

Photos Courtesy Kathryn Holcomb, PhD

The first study evaluated horses’ physiological and behavioral responses to shade. Twelve adult horses were housed individually for five days in either completely shaded pens (SH) or completely unshaded pens (SUN), and then traded places for five days to serve as their own controls. Horses in the SUN group had higher RT, RR, and SK than SH horses, and SUN horses also stood near water more often and consumed more water than horses in the shade group.

The second study sought to quantify horses’ preference for shade. Researchers housed 11 adult horses individually for five to seven days in half-shaded pens.

“Horses were observed in the shade 7.1% more during daylight hours than would be expected by chance,” Holcomb said. “We defined ‘in shade’ as two or more hooves in the shade.”

“Time of day was a significant factor,” Holcomb said. She said researchers observed the horses in shade more frequently at midday and late afternoon, corresponding to peak solar radiation (midday) and, to their surprise, just after peak ambient and black globe temperatures (late afternoon).

The team concluded that shade provides horses significant physiological benefits, even with limited use, and when given the choice mature horses show a preference for using shade under summer conditions, Holcomb said.

She noted that these studies addressed preference and benefits, and that additional research is needed to determine if and under what conditions horses require shade.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.



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