We received several questions about this article, so we’ve worked with the researchers to get some additional information and clarify a few points on resting surface area requirements and bedding depth. We updated this article on Nov. 19 at 2:40 p.m.

If you’ve ever carted wheelbarrow loads of soiled bedding to the manure bin, you’ve probably wondered, at one time or another, if your horses really need all those shavings or straw in their stalls. Wonder no more: New research shows that bedding does matter, and so does the amount of bedding available. In fact, the greater the surface area of soft bedding (straw or shavings) available—that is, the size of the area that is bedded—the more time horses spend lying down.

Longer times spent lying down are important, as they allow horses to recover from stress and exercise, promoting better equine welfare, said Christina Rufener, a master’s student at the Ethology and Animal Welfare Unit at ETH Zurich, in Switzerland. She presented her findings at the 10th Annual Swiss Equine Research Day, held in April in Avenches.

Rufener and colleagues assessed 38 horses divided into eight groups, each of which lived in group housing (a group stall, plus access to an outdoor run with firm footing) and were tested in four different bedding scenarios based on Swiss welfare requirements. The law requires that horses be offered a minimum surface area of bedding—straw or shavings—as a function of their body height. For example, a 17-hand (170 cm) horse in a group housing situation should have at least 75 ft² (7.5 m²) of “resting area.”