01/24/2026
Today in Equine Math classโฆ. ๐
โ๏ธ ๐๐ข๐ง๐ญ๐๐ซ ๐
๐๐๐๐ข๐ง๐ : ๐๐ก๐ฒ ๐๐๐ฒ ๐๐๐ญ๐ญ๐๐ซ๐ฌ โ๏ธ
๐ฅ ๐๐๐ฒ = ๐๐ง๐ญ๐๐ซ๐ง๐๐ฅ ๐๐๐๐ญ
The best way to warm up your horse in the winter is to provide hay!
Hay is primarily digested in the hindgut through a process known as fermentation, which generates a significant amount of metabolic heat. This means hay acts as a fuel of sorts for the horseโs very own internal furnace, helping warm them from the inside out.
โก ๐๐จ๐ฅ๐ ๐ฐ๐๐๐ญ๐ก๐๐ซ ๐ข๐ง๐๐ซ๐๐๐ฌ๐๐ฌ ๐๐ง๐๐ซ๐ ๐ฒ ๐๐๐ฆ๐๐ง๐๐ฌ
Not only that, but when the weather is cold, a horse has increased caloric demands, as they require extra energy to maintain body temperature. This means providing extra hay during a cold snap not only helps generate internal heat, but also helps meet the additional calorie requirements associated with cold weather.
๐พ ๐๐ก๐๐ง ๐ก๐๐ฒ ๐ข๐ฌ ๐๐๐ ๐ข๐ง ๐ฌ๐๐ญ ๐๐ฆ๐จ๐ฎ๐ง๐ญ๐ฌ
While I provide unlimited access to forage year-round, I have been to many barns that provide set amounts of hay at mealtime. This can become problematic when temperatures fall below the horseโs lower critical temperature (LCT).
๐ก๏ธ ๐๐ก๐๐ญ ๐ข๐ฌ ๐ญ๐ก๐ ๐๐จ๐ฐ๐๐ซ ๐๐ซ๐ข๐ญ๐ข๐๐๐ฅ ๐๐๐ฆ๐ฉ๐๐ซ๐๐ญ๐ฎ๐ซ๐ (๐๐๐)?
The LCT represents the temperature at which a horse begins to expend additional energy to stay warm. The farther below the LCT the temperature falls, the more energy the horse must use to maintain body temperature.
The LCT can vary based on the individual horse, acclimation to the current climate, hair coat, and weather conditions.
Specifically:
โ๏ธ A horse acclimated to a cold climate with a long winter coat has an LCT of 18ยฐF
๐ค๏ธ A horse acclimated to a warm climate with a short coat has an LCT of 41ยฐF
๐ง๏ธ A wet hair coat is especially important, as it can increase the LCT to 59ยฐF
๐ ๐๐ก๐ฒ ๐๐จ๐๐ฌ ๐ญ๐ก๐ ๐๐๐ ๐ฆ๐๐ญ๐ญ๐๐ซ?
This value is important because for every degree below the LCT, a horseโs energy requirements increase by approximately 1%.
For example, if you have a horse acclimated to a cold climate and the outside temperature is 0ยฐF, their energy requirements increase by 18%.
๐งฎ๐๐๐ญ๐๐ซ๐ฆ๐ข๐ง๐ข๐ง๐ ๐ก๐จ๐ฐ ๐ฆ๐ฎ๐๐ก ๐๐ฑ๐ญ๐ซ๐ ๐ก๐๐ฒ ๐ญ๐จ ๐๐๐๐
To determine how much additional hay is required, you must first estimate the horseโs baseline energy requirements. I personally use the NRC Requirements of the Horse โ Working Doc, where I input body weight and current life stage to estimate maintenance energy needs.
Once this value is determined, I use the digestible energy (calories) reported on my hay test to calculate how many additional pounds of hay are needed to meet the increased energy demand.
๐ฟ ๐๐ฎ๐ญ๐ญ๐ข๐ง๐ ๐ข๐ญ ๐ข๐ง๐ญ๐จ ๐ฉ๐ซ๐๐๐ญ๐ข๐๐
As you can see from this example, providing nearly 10 additional pounds of hay per horse may not always be feasible. This is why I keep a high-quality alfalfa hay on hand, which allows me to help meet increased caloric demands in a quantity the horse can realistically consume.
I think it is also important to remember that blanketing or housing horses in insulated or heated barns may alter these recommendations, as the body does not need to work as hard to stay warm. This equation helps provide an estimate but we can expect some variability!
โ
๐๐จ๐ง๐๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง
On these cold days, make sure the first thing you reach for to help your horse stay warm is some extra hay! Not only does it fuel their internal furnace, but it also provides additional calories they require to maintain their core body temperature. This equation can help estimate how much extra hay may be needed during cold weather!
Stay warm out there โ๏ธ๐ด
Dr. DeBoer
