Wintertime Equine Nutrition: 3 Facts Help horses weather the winter with insight from equine nutritionists and a veterinarian

From Aimee Robinson, Valley Vet Supply

While impressively stout yet entirely fragile, horses require a great level of care, especially as it relates to their nutrition over the winter. 

“Many horse owners may not realize they actually need to feed horses differently in the wintertime than they do in the summertime,” Jyme Nichols, PhD, director of nutrition at Stride Animal Health, shared in an interview with Valley Vet Supply.

Here are three main facts to consider.

Fact 1: A Horse’s “Thermoneutral Zone” Directly Impacts Their Nutritional Needs.
“The first thing that I think is important for everybody to understand is a term that sounds a little bit intimidating — thermoneutral zone,” Dr. Nichols said. “This is basically the temperature outside in which a horse can maintain their own core body temperature without having to exert any extra effort to regulate either their heat loss or heat gain.”

Horses in the United States have an average thermoneutral zone between 40 and 80 degrees, which means horses near the low end of their thermoneutral zone will have to use extra energy (thus calories) to maintain heat.

To identify whether your horse is outside of their thermoneutral zone, “You want to pay attention to whether or not they’re using any natural defenses to that cold weather,” explained Brittany Rahm, nutrition consultant at Stride Animal Health.
These natural defenses can include:
  • Shivering
  • Standing with tail to the wind, head lowered
  • Seeking shelter
Dr. Nichols followed up, “Anytime you combine cold temperatures on top of moisture – wind, ice and snow – a horse will have to increase their heat production and will need to consume more calories. Additionally, young horses or underweight horses are going to hit that lower, critical temperature and get colder faster than a mature horse or a horse that’s going into wintertime with really good body condition.”

An especially important detail for those traveling for competitions or pleasure with their horses is that it takes two weeks to a full month for horses to readapt to a new ambient temperature.

“When traveling, be mindful if you're going a long distance or to a region that has a very different temperature range than what you’re coming from – your horse may struggle a little bit more to retain heat or try to get rid of it – depending whether you’re going to a colder climate or a hotter climate,” said Dr. Nichols.

Fact 2: A Horse’s Feed Sources Will Help Them Maintain Warmth, in Addition to Weight.
It’s important to understand “metabolic heat production” as it relates to increasing a horse’s feed during cold temperatures.

Dr. Nichols explained, “Think of a horse’s digestive system, or their hind gut, as a furnace. The more the microbes in the horse’s hind gut are able to digest and ferment – especially fibers – the more heat that can be generated for that horse. That’s part of what goes into keeping them warm.”

Fact 3: As Weather Changes, So Should a Horse’s Diet, But Not in the Way Some May Think.
“A lot of times, people can get hung up thinking, ‘I need to change my horse’s grain, or I need to change how much grain I feed,’” Dr. Nichols said. However, is either necessary? Not exactly, but there are some other aspects for horse owners to consider.

While a well-meaning sentiment, increasing grain can be harmful to a horse’s health – heightening colic risk and more – and secondly, doing so may not be enough to help a horse maintain their warmth when they need it most.

“Increasing the amount of hay is the best way to increase heat production and keep a horse warm during winter,” Dr. Nichols said. “Horses will naturally increase the amount of hay that they eat, based on the temperatures dropping.”

Regarding how much more hay to provide – remember that the average thermoneutral zone for horses in the U.S. is between 40 and 80 degrees. Dr. Nichols said, as a general rule of thumb, for every one-degree Fahrenheit below the lower range of 40 degrees, horses will need an extra 200 calories.

“So, to put that in perspective, your average hay is going to have between 800 to 1,000 calories per pound. Let's say you've got a 10-degree drop – you're going to need an extra 2,000 calories. All I did there was just take that 10 degrees times 200 calories, and that gets me to 2,000 calories, which is roughly 2 to 3 lbs. extra hay per day. So, if you're feeding small square bales of grass hay, that's probably going to be an extra flake, maybe an extra two flakes.”

Horse owners will need to increase their horse’s hay intake, but what about their grain? When the temperatures drop, upping feed is a common practice, but not recommended. Dr. Nichols gave two specific horse health examples: should horses be fed either a fortified feed or cereal grains, such as whole corn and oats?

Example 1, fortified feed increase – if horsemen are feeding a fortified grain at a recommended level of 4 lbs. per day, then increase by 1 lb. per day. That feed is designed to meet all vitamin, mineral requirements, amino acid requirements, etc., at 4 lbs. per day. While that extra pound may not be more harmful, it will provide some extra calories, but the calories will be more quickly digested. This means the increased grain does not provide horses with long-term heat production, like hay does.

Example 2, cereal grain increase – say horsemen are feeding a whole corn/oat mix at 4 lbs. per day and decide to double it. Corn and oats are really high in starches and sugars, which puts a really heavy load of sugar on the digestive tract that the small intestine can't digest very well or very quickly. You can then have an overspill of starch into the hind gut of the horse, impacting the balance of the good bacteria in that gut and presenting colic issues; it can also cause founder or laminitis issues in some horses.

“You want to keep your grain level the same. If you're going to increase anything, the most important thing to do is increase the hay and consider a supplement that will keep them drinking,” Rahm said.

For senior horses or horses with poor dental conditions, both Rahm and Dr. Nichols recommend feeding forage pellets, such as Timothy or alfalfa hay pellets, or even beet pulp shreds, which all have similar benefits as long-stem hay forage.

“For horses who are underweight, it is important to try to improve their body condition, which will support their thermoregulation and overall health. In addition to increasing their total hay intake, we recommend adding a high-quality protein and energy supplement to help support healthy weight gain,” said Tony Hawkins, DVM, technical service veterinarian at Valley Vet Supply.

Bundle up, stay safe, and keep in mind these three facts to help your horse weather the winter.

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