Heading out to do barn or farm chores in winter means bundling up with layers to fend off penetrating cold. Horses have their own built-in insulation of a winter hair coat and a layer of fat to protect against cold temperatures. As keepers of our horses, we also often provide shelter and/or blankets to help them conserve warmth in their bodies. But what other strategies can we implement to help our horses stay warm?
What do horses consider cold?
Not all cold weather conditions sap energy from horses if they are sufficiently protected with hair and at least a thin insulating layer of fat. The point at which a horse uses more energy to maintain body warmth beyond normal metabolic needs is called the lower critical temperature (LCT). Generally, this is around 45 degrees Fahrenheit. For every 10 degrees Fahrenheit below this critical temperature, a horse needs to consume approximately 10% more calories to stay warm without losing weight. For a horse that eats 20 pounds of hay per day, adding another two pounds of hay each day helps him better manage a cold snap.
How much more feed a horse needs depends on certain climatic changes. Take a horse in the Rocky Mountains as one example. Shortening daylight hours and steadily increasing cold temperatures through the progression of autumn months prepare this horse for upcoming winter weather. He grows a good hair coat and eats more to accumulate a layer of fat. Then consider this same location with the horse brought into the barn at night, with or without a blanket. This individual is not as acclimatized to outside weather conditions, so his LCT will start at a higher temperature range when he is turned out compared to the horse that lives outside around the clock.
Regardless of the living arrangement and how accustomed a horse is to his environment, once the lower critical temperature is reached, without added groceries, he will begin to lose weight. This is particularly true if cold conditions persist, as they tend to for many months in northern parts of the United States.
It is likely that a working horse is provided more amenities than an idle horse living full-time in turnout. Yet a working horse needs to consume more calories than an idle horse because of exercise demands from training and competition stress. Because of fitness, a working horse tends to have a leaner frame with less fat covering than an idle horse. Therefore, he has less fat insulation to shield him against the cold. These many factors must be accounted for when considering feeding strategies for working horses in winter.
A Starting Point
It is well known that digestion of forage is a powerful weapon against the cold. The hindgut of the horse evolved to take in large amounts of forage (roughage) each day over small, frequent meals. The metabolic processes of digestion turn this food source into energy and produce a byproduct of heat.
The hindgut works like an internal combustion chamber to warm a horse from the inside out. A shivering horse that has cleaned up his feed might need extra groceries. Shivering is a normal response to cold; muscle shaking generates warmth.
In general, horses consume 1.5-2% of their body weight each day, preferably in the form of forage (hay and/or pasture). For a 1,000-pound horse, this amounts to 15-20 pounds of roughage per day. It is possible that a horse would need to consume as much as 3% of his body weight if he is in regular or strenuous exercise in the face of extreme cold. Using a scale to weigh the hay lets you know exactly how much you are feeding.
Not all horses can consume enough forage to maintain a proper weight, so those individuals might need to be supplemented with more energy-dense supplemental feeds, such as complete feed pellets, grain, beet pulp and/or fat sources.
Grain and pelleted feed products don’t generate heat from digestion like forage does; the one thing they do is help maintain body weight and add calories to build insulating fat. Fat deposition takes time to develop, so in the face of a sudden cold snap, the best strategy is to offer more hay, which provides digestive heat immediately, while also being relatively low in starch and sugars.
When possible, a hard-working horse should have hay available at all times. Not only does this enable a horse to regulate his intake, but it is also a means of protecting against colic, gastric ulcer syndrome, boredom, and attendant vices such as pacing, wood chewing, and dirt consumption. Have your veterinarian check and attend to your horse’s dental care once or twice a year to ensure optimal chewing of forage. This achieves the best digestive efficiency and weight management while limiting the risk of choke, diarrhea, or colic.
Exercise also helps improve intestinal motility, so besides routine training demands, turnout is an additional help to optimize digestive health.
If horses are housed in a group living situation, it is important to ensure that each individual has a chance to eat his fill without being pushed away from the hay. Hay that is spread into many piles spaced a distance apart enables more timid horses to eat without being run off by dominant herd members.
Keep in mind that as much as 25% of hay fed on the ground might be rendered unpalatable if stomped on by horse feet, or some of it might blow away. Factor this in when determining how much to feed.
Acquiring a fresh crop of hay that is green goes a long way toward providing the essential vitamins A and E. Stress creates a potential for vitamin deficits; some horses can benefit from supplementation with vitamin E (1,000 IU/day) and vitamin C (3-5 grams twice a day).
Hay left over from previous seasons can be mixed with the newer batch to stretch your budget while still providing ample vitamins from the fresher crop. It might also be prudent to supplement forage with a multi-vitamin mix during winter months, when pasture nutrients and sunshine are in low supply.
To ensure good airway health, wetting the hay before feeding decreases inhaled dust and debris that can cause or exacerbate respiratory allergies. Offer only as much wetted hay as can be consumed before it freezes.
Some recommendations suggest that during winter cold months, horses need as much as 25% more energy intake—especially those in work. This can be provided in part by a well-balanced feed supplement. Complete pelleted feed is the best choice, as it is high in fiber with ample energy components along with important vitamins and minerals.
Also, soaked beet pulp pellets provide high fiber and energy without adding sugars or starch to the diet. Soaking the beet pulp pellets in water also helps with winter water intake. Be sure that the amount of beet pulp mash offered is consumed fairly quickly before it has a chance to freeze.
Fat supplementation with rice bran and/or vegetable oil is an excellent way to provide calories to the working horse without adding sugar or starch. Start slowly with ¼ cup oil or rice bran once or twice a day, slowly working up to one cup twice daily over the course of two to three weeks. All dietary changes of any kind should be done slowly over a two- or three-week period.
Some working horses might fare best if supplemented with a proportion (no more than 30% of forage) of alfalfa, either as hay or in pelleted or cubed form. Alfalfa is also known as a heating feed in that its digestion contributes to internal body warmth. In summer, this might be a disadvantage to an actively ridden horse; in winter, it could help to fend off the cold.
The least useful—and potentially the most harmful—supplement to offer is grain or sweet feed such as corn, oats or barley, with or without molasses. These grains are high-starch feeds, which often bypass stomach digestion and enter the large intestine, where they ferment.
A subsequent drop in pH that creates an acid intestinal environment adversely affects the normal intestinal microbiome. Disruption of the intestinal microbial balance leads to all kinds of problems, such as gaseous colic, diarrhea, leaky gut syndrome and accompanying systemic inflammation. High-grain diets, especially if five pounds or more are fed at one feeding, also contribute to the risk of gastric ulcers.
A critical nutrient for any horse at any time of the year is water. In winter, this is especially important because insufficient water intake often leads to impaction colic.
Water should be ice-free at all times; horses drink better if water is at least 40-50 degrees Fahrenheit. Tank heaters and heated waterers in the barn are helpful to accomplish this but should be well-grounded to avoid incidental electric shock currents that would discourage drinking. These units should be checked at least once daily to ensure proper function and the presence of unfrozen water.
Consider the placement of water sources. If the primary source of water is a distance from the barn, paddock or loafing shed, heavy snow and ice can render the water fairly inaccessible without the horse making a concerted effort. Any decrease in water intake potentially induces problems, especially with the digestive tract. Monitor a horse’s manure output, consistency, and quality.
Hay requires considerable water for digestion, at least 2-4 pints of water per pound of feed. Under normal resting conditions in winter, a horse should consume at least 7-10 gallons of water a day, and far more—at least double—if exercised, especially if sweating.
Monitoring Body Condition
Those horses left unclipped with a dense hair coat might appear to be in good condition, but it is important to check periodically that there isn’t a gaunt frame beneath that winter hair coat.
As you run your fingers across the horse’s thorax, you should just be able to feel the last two ribs. If more ribs are easily felt, the horse is too thin; if no ribs are felt, the horse is likely overweight. Shoot for a body condition score of 5 or 6.
At least 60% of any horse’s diet should be comprised of forage in one form or another—hay, pasture or hay cubes, as examples.
A horse in active work might also need supplementation with energy-dense nutrients, preferably those that are not high in starch or sugar. This can be accomplished using complete feed pellets, beet pulp and oil, and/or rice bran fat supplementation.
Remember that ice-free water should be available at all times.
For lean horses and those in hard work, cold weather often necessitates feeding more forage to help heat the horse from within through digestive metabolism. Adding some alfalfa could help.
Work with your veterinarian and your local nutrition specialist to develop a program to keep your horses healthy and warm this winter.