Tips for healthy horses and safe facilities when temperatures plummet

Whether you love winter or would rather pass on it, freezing temperatures, bitter winds, snow, and ice all bring challenges to managing horses and the farm. With some planning ahead, these few straightforward horsekeeping tips can help keep your farm running smoothly and your horses healthy when winter weather arrives.

Thermoneutral Zones in Horses

When a horse can maintain his body temperature without expending additional energy to stay cool or warm, the ambient temperature falls within his thermoneutral zone, with the lower critical temperature marking the bottom of this spectrum. This critical temperature is a range estimated between 40 and 5 degrees Fahrenheit, explains Devan Catalano, PhD, assistant professor and equine specialist at Colorado State University, in Fort Collins.

“Horses have a thermoneutral zone—as do humans,” says Catalano. “At the upper level, horses lose weight because it’s too hot. In the winter is the flipside, in which horses need more than their baseline diet to hold their weight. This number is called the lower critical temperature; this range depends on the climate to which your horse is acclimated and the horse’s hair coat.

“So, a horse in Montana with a full winter coat will have a much lower critical temperature than a clipped horse in Florida, for example,” she adds. This lower critical temperature can play a role in horse owners’ decisions in winter, including diet and blanketing.

Equine Nutritional Considerations for Winter

Free-choice hay? Warm mash? Many horse owners turn to these standbys when frigid temperatures arrive, but what horses need depends on each situation. “Winter nutrition concerns must consider factors like critical temperature and how horses are housed,” says Kathleen Anderson, PhD, professor and extension horse specialist at the University of Nebraska, in Lincoln. “From a nutrition standpoint, for horses housed indoors, particularly in a heated barn, not much will change.

“It’s important to understand horses generate more body heat when they digest forages, as opposed to concentrates,” she continues. She recommends offering an additional pound of hay per day for every 10 degrees below the horse’s lower critical temperature and not feeding any additional grain (concentrate). “In general, at about 20 F, begin increasing hay. Be sure to provide good-quality hay; dusty hay may impact your horse’s respiratory system, leading to acute or even chronic cough.”

Here’s how Catalano figures out how much forage a horse needs. “For every degree below a horse’s lower critical temperature, there is about a 1% increase in the horse’s energy needs, which sounds like a lot but is actually about 3 pounds of hay for a 20-degree drop,” she explains. “You can estimate that if your horse’s critical temperature is about 20 F, when temperatures reach zero degrees, you should feed an extra 3 pounds of hay.

“We want to keep forage in front of our horses as much as possible, whether they are stalled or live outdoors,” she adds. “Forage is beneficial for overall hindgut health, keeping everything moving through the system and, as microbes in the hindgut digest forage, this generates heat with the hindgut acting like a furnace