Feeding Horses in Winter: Adjusting Diet for Cold Weather

Reviewed by Dr. Ali Ehtisham, DVM

Winter brings some of the most demanding nutritional challenges a horse owner will face. As temperatures plummet, a horse's body is working around the clock to maintain its core temperature, burning through calories at a rate that a summer feeding programme simply cannot support. Understanding exactly how cold weather changes your horse's energy requirements — and knowing how to respond with the right feed adjustments — is one of the most important skills you can develop as a responsible horse keeper.

Why Horses Need More Food in Winter

Horses are warm-blooded mammals with a core body temperature that must stay within a narrow range to sustain life. When the ambient temperature drops below what is known as the lower critical temperature — roughly 18 degrees Fahrenheit (around minus 8 degrees Celsius) for a healthy, unclipped horse with a good winter coat — the animal's body begins a process called thermogenesis, actively generating heat to compensate for what is lost to the environment. This process consumes a significant quantity of energy, and that energy must come from somewhere. If it does not come from feed, it will come from the horse's own body reserves, leading to weight loss and potentially serious health consequences over a prolonged cold spell.

One of the most remarkable and useful aspects of equine digestive anatomy is the role the hindgut plays as a natural furnace. The horse's large intestine and cecum house billions of microorganisms that ferment fibrous plant material — primarily hay — and in doing so they produce heat as a direct by-product. This is why equine nutritionists consistently emphasise that hay, rather than grain or other concentrates, should be the primary tool for warming a horse from the inside out. A horse munching steadily on a generous hay net on a freezing night is not just satisfying its hunger; it is actively fuelling an internal heating system that has evolved over millions of years.

Horses who are underfed during winter will draw on their fat reserves first, and once those are depleted they will begin to metabolise muscle protein. A horse that enters winter in poor body condition has far less buffer against the cold than one that arrives in autumn at a healthy weight of 5 or 5.5 on the Henneke Body Condition Score scale. Planning ahead, building condition during autumn when grass is still available, and monitoring throughout the winter months are all essential elements of sound cold-weather management.

How Much Extra Hay Does a Horse Need in Winter?

The baseline recommendation for forage intake is 1.5 to 2 percent of a horse's body weight per day in dry matter. For a 1,000-pound (450 kg) horse, that means roughly 15 to 20 pounds of hay daily under mild conditions. In winter, that figure needs to be recalculated based on actual weather. As a general rule of thumb used by many equine nutritionists, energy requirements increase by approximately 1 percent for every 10 degree Fahrenheit drop in temperature below the lower critical threshold. On a day when the temperature sits at minus 10 degrees Fahrenheit — 28 degrees below the critical threshold — that same horse may need 28 percent more calories than its baseline, which translates to roughly 25 to 28 pounds of quality hay.

Wind and wet conditions compound the effect significantly. A horse standing in a cold rain or a biting wind loses body heat far faster than one in still, dry air at the same temperature. The windchill equivalent temperature should influence your feeding decisions just as much as the thermometer reading. A 30-degree Fahrenheit day with a 20 mph wind can feel metabolically equivalent to a 15-degree day in calm conditions.

To apply this practically, weigh your hay rather than estimating by flake, since flakes from the same bale can vary widely in weight depending on how the hay was baled. Investing in an inexpensive hanging scale for the feed room removes the guesswork and ensures you are genuinely meeting your horse's needs rather than simply assuming the ration is adequate. Providing hay ad libitum — that is, free access at all times — is the safest approach for most horses during cold snaps, because they will self-regulate intake according to their energy needs. The exception to this is horses prone to metabolic conditions such as laminitis or insulin resistance, for whom ad libitum forage is not appropriate and whose feed management should be guided by a veterinarian.

Monitoring Body Condition Through a Thick Winter Coat

One of the most common mistakes horse owners make in winter is assuming a horse looks well because it looks well-covered. A lush, long winter coat can hide dramatic weight loss beneath it, creating a false sense of security that may only be shattered when the coat is shed in spring to reveal a horse in poor condition. By that point, weeks or months of nutritional shortfall have already taken their toll. The solution is simple but requires discipline: use your hands, not just your eyes.

The Henneke Body Condition Scoring system provides a structured method for assessing a horse's fat coverage on a scale from 1 (poor — severe emaciation) to 9 (extremely fat). The key assessment areas are the neck, withers, shoulder, ribs, loin, and tailhead. A score of 4 to 6 is generally considered healthy for most horses, though breeding animals and horses heading into winter may benefit from sitting at the higher end of that range to provide a buffer. To score accurately in winter, you must run your hand firmly and flatly over each area. Healthy fat coverage over the ribs should feel like running your hand over the back of your knuckles — you can feel the structure but it is cushioned. A score of 3 or below means ribs, spine, and hip bones are prominent and easily felt, and the feed ration must be increased immediately.

Commit to a monthly hands-on body condition check as a non-negotiable part of your winter routine. Mark it in your calendar. A horse losing weight in January will be in far worse shape by February if the problem goes undetected, and early intervention with additional forage and targeted supplementation will nearly always cost less and cause less harm than emergency management of a severely underweight animal.

Water in Winter: The Critical Risk

Dehydration is one of the most serious and underappreciated risks of winter horse management. Horses tend to drink significantly less water when it is cold — studies have shown that horses offered water at 32 to 38 degrees Fahrenheit drink up to 40 percent less than horses offered water at around 45 to 65 degrees Fahrenheit. This reduced intake is not a benign quirk; it dramatically increases the risk of impaction colic, which is one of the most common reasons for veterinary emergency calls in winter. Impaction colic occurs when gut contents become dry and compacted, often in the large colon, causing a potentially life-threatening blockage.

The most effective way to encourage adequate water consumption is to ensure the water is never icy cold or frozen. Heated water troughs and submersible bucket heaters are the gold-standard solution and are widely available at reasonable cost. If electricity is not available in your field or stable, breaking ice at minimum twice daily and offering buckets of lukewarm water at each feeding time will help, though this requires consistent effort and is less reliable during sustained freezes. Research from Penn State University found that horses drank almost 40 percent more water when it was offered at a temperature of around 45 to 65 degrees Fahrenheit compared to near-freezing water, which is a compelling argument for investing in some form of heating.

A useful monitoring habit is to track roughly how much water your horse consumes each day. An adult horse at maintenance needs a minimum of 5 to 10 gallons of water per day, and this requirement increases with exercise, higher dry matter intake from hay, and lactation. If you notice your horse is drinking less than usual, offer warm water at each feed, consider adding a small amount of loose salt to its feed to stimulate thirst, and contact your veterinarian if reduced intake persists for more than a day or is accompanied by any signs of abdominal discomfort.

Should You Increase Concentrate Feed in Winter?

The forage-first principle is the foundation of winter nutrition: always look to increase hay or haylage before reaching for the grain scoop. This is because the fermentation-generated heat from hindgut fibre digestion is uniquely valuable in cold conditions, while concentrates like grain, pellets, and cubes produce comparatively little metabolic heat during digestion. Beyond the warmth factor, an over-reliance on concentrates without a matching increase in forage can disrupt the microbial balance of the hindgut, increasing the risk of colic and laminitis.

That said, there are genuine situations where concentrates are warranted. Horses in moderate to heavy work have elevated calorie requirements that forage alone may not efficiently meet. Horses who are underweight and struggling to maintain condition despite maximum forage intake need the calorie density that concentrates provide. Elderly horses with poor dentition often cannot chew long-stem hay effectively enough to extract adequate nutrition from it, and concentrate feeds or soaked alternatives become essential. In all these cases, any increase in concentrate should be made gradually over seven to fourteen days to allow the hindgut microbiome time to adapt, and should be divided across as many small meals as is practical rather than delivered in one or two large feeds.

Oil is an often-overlooked energy source that can be added to rations as a calorie-dense, non-heating supplement. Vegetable oils such as soya oil provide approximately 2.5 times more energy per pound than carbohydrate-based feeds, with a low glycaemic impact, making them useful for horses who need extra calories without the excitability or metabolic risks associated with high-starch feeds. Introduce oil very gradually, starting at no more than 25 ml per day and building to a maximum of around 200 ml for most horses.

Feeding the Senior Horse in Winter

Older horses — generally those aged fifteen and above — face additional challenges in winter that make nutritional management more demanding. Dental deterioration is among the most significant: ageing horses frequently develop wave mouth, hooks, missing teeth, or painful dental conditions that impair their ability to chew and properly process long-stem hay. A senior horse with poor dentition may appear to eat enthusiastically but is actually wasting a large proportion of its forage as partially chewed, spat-out wads known as quids. If you observe this behaviour, a dental examination should be scheduled promptly, and the feeding programme should be adjusted to include soaked hay pellets, soaked sugar beet pulp, complete senior feeds, or soaked haylage to ensure the horse is actually able to absorb the nutrition it needs.

Senior horses also tend to have reduced digestive efficiency, meaning they extract less energy from the same quantity of feed than a younger horse would. This makes maintaining body condition significantly harder and means that what looks like an adequate ration on paper may be genuinely insufficient in practice. Senior-formulated feeds are designed to address this with higher fat content, more digestible fibre sources, and targeted supplementation with vitamins and minerals that older horses may absorb less effectively from standard diets.

Pituitary Pars Intermedia Dysfunction, commonly known as Cushing's disease or PPID, is another important consideration for senior horse owners. PPID is prevalent in horses over fifteen and affects the coat, metabolism, immune function, and susceptibility to laminitis. Horses with PPID may have a coat that does not shed normally and may struggle to regulate body temperature efficiently, making them more vulnerable to cold stress. They also require careful management of starch and sugar intake to reduce laminitis risk, which restricts the use of many conventional energy-dense feeds. Any senior horse showing signs of Cushing's — a long, curly coat, pot belly, abnormal sweating, or muscle wasting — should be tested and managed under veterinary guidance, with a feeding plan tailored to the specific metabolic demands of the condition.

Feed Storage and Safety in Winter

Cold and wet conditions create specific challenges for feed storage that, if ignored, can lead to spoilage, mould growth, and serious health risks. Hay stored outdoors on the ground is particularly vulnerable to moisture penetration from below and from the sides, and mouldy hay can cause respiratory problems, digestive disturbance, and in severe cases mycotoxin poisoning. Hay should ideally be stored under cover on pallets or bearers that lift it clear of any ground moisture, with good ventilation around the stack to prevent condensation buildup.

Bagged concentrates and compound feeds should be kept in waterproof, rodent-proof containers. Bins with tight-fitting lids, galvanised metal containers, or purpose-made feed storage units all work well. Damp concentrate feed can spoil quickly, and feeds with high oil content are particularly prone to rancidity in fluctuating temperatures. Check the condition of feeds regularly throughout winter and discard any that smell musty, show visible mould, or have an unusual colour or texture. The cost of replacing a bag of feed is trivial compared to the veterinary bills and distress associated with a horse made ill by contaminated food. Keep a consistent stock rotation system, using older feed before newer deliveries, and try to order in quantities that will be used within a few weeks rather than purchasing bulk stores that sit for months.

Frequently Asked Questions

How much more hay does a horse need in winter?

A horse typically needs roughly 1.5 to 2 percent of its body weight in forage per day under normal conditions, but in cold weather that requirement can rise to 2 to 2.5 percent or more. For every 10 degrees Fahrenheit the temperature drops below the horse's lower critical temperature, energy requirements increase by approximately 1 percent. A 1,000-pound horse that normally eats 15 to 20 pounds of hay daily may need 25 to 30 pounds on the coldest days, so it is wise to calculate requirements based on your specific horse's weight, condition, age, and workload rather than relying on a single blanket figure.

Should I feed my horse more grain in winter?

The forage-first principle holds true in winter: increasing good-quality hay should always be your first response to cold weather, because the fermentation of fibrous feed in the hindgut generates heat from within. Concentrates such as grain or pelleted feed are appropriate only when a horse cannot physically consume enough hay to meet its energy needs — for example, elderly horses with dental problems, horses in heavy work, or those who are losing condition despite unlimited forage access. If you do increase concentrate, do so gradually to avoid digestive upset, and work with your veterinarian or an equine nutritionist to ensure the overall ration remains balanced.

How do I stop my horse's water from freezing?

The most reliable long-term solution is a thermostatically controlled heated water trough or a submersible bucket heater, both of which maintain water at a drinkable temperature without making it uncomfortably warm. In the absence of electric heating, breaking ice at least twice daily and offering slightly warmed water at meal times will encourage intake, though this approach requires consistent effort and horses may still drink less than they need. Insulated trough covers, placing troughs in sheltered or south-facing locations, and using dark-coloured containers that absorb solar heat are useful supplementary strategies but rarely sufficient on their own during a hard freeze.

How do I know if my horse is losing weight in winter?

Because a thick winter coat visually disguises weight loss very effectively, you must use your hands rather than your eyes: run your flat palm firmly along your horse's ribs, spine, and hindquarters at least once a month. Using the Henneke Body Condition Scoring system — a scale from 1 (emaciated) to 9 (obese) — gives you a consistent, repeatable framework; a healthy horse should score between 4.5 and 6 throughout winter. If you can feel the ribs easily without applying pressure, or if the spine feels sharp and the hindquarters appear sunken even beneath the coat, the horse is likely losing body condition and its feed ration should be reviewed urgently.

Does a horse need a rug to stay warm in winter?

Whether a horse needs a rug depends on several factors including whether it has been clipped, its age and health status, its breed, the severity of the weather, and whether it has access to adequate shelter and forage. Horses with a full, natural winter coat, good body condition, free access to shelter, and unlimited hay can remain comfortable in temperatures well below freezing without a rug. Clipped horses, elderly or underweight horses, fine-skinned breeds such as Thoroughbreds, and horses kept in very wet and windy conditions are the most likely to benefit from appropriate blanketing, but over-rugging a healthy horse can suppress its natural ability to regulate body temperature through coat erection.

For more detailed guidance on building a complete horse feeding programme, see our horse feeding guide. You may also find it helpful to read about what horses eat across the full range of forage and concentrate options, and if you manage an older horse, our senior horse care guide covers the specific nutritional and health needs of horses aged fifteen and above.

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Disclaimer: This article is for educational purposes only. Always consult a licensed veterinarian for your pet's health and medical needs.