Photo: Horse in a snowy field looking over a fence.

Cooperative Extension Fact Sheet FS1143

Winter Feeding for Horses

Carey Williams, Extension Specialist in Equine Management
Sarah Ralston, VMD, PhD, DACVN, Retired

Winter conditions vary dramatically among the world's various regions, as do the tolerances of individual horses to cold weather stressors. Therefore, it is impossible to give exact recommendations regarding nutritional needs that would be applicable to all horses and regions. However, there are general nutritional concerns that always need to be addressed as the weather gets colder. These are insuring adequate caloric (energy) and water intake and recognizing situations where supplemental nutrients may be necessary to maintain a horse's optimal health and well-being. These concerns will be addressed in this fact sheet, which will also provide some basic feeding recommendations and help to dispel some common myths regarding feeding horses in winter.

Energy Concerns

Figure 1. Three horses on a snowy day, two comfortable without blankets and one needing a blanket.

During the winter months, many horses will need extra energy to help them maintain their body temperature without decreasing body weight or creating stress due to multiple days of discomfort (cold stress). On average, it has been estimated that the average horse will need about 25% higher energy intake during the coldest winter months. This is only a rough estimate and should not be implemented without considering the following factors. For each degree Fahrenheit the air is below the horse's lower critical temperature (LCT, the temperature below which the horse will start to use more energy for maintaining body warmth than their normal expenditure) the caloric needs will increase by about 1%. However, the LCT of an individual horse will depend on the temperatures to which it is accustomed, the amount of body insulation (i.e., length of the hair coat, type of blanket, and amount of body fat), and protection provided by shelters. For example, a lean horse stabled in a heated barn in Georgia with a clipped hair coat may have a LCT of 50 °F, whereas a shaggy, overweight horse accustomed to living outdoors with only three-sided run-in sheds in Michigan may have a LCT of 30 °F or lower. If a horse is shivering, it is a good indication that its LCT has been reached. Piloerection (when the hair coat is standing on end instead of lying flat) and horses seeking shelter from wind or precipitation are also good indicators that they need higher energy intake. If cold stress is sufficiently prolonged (more than one or two days) and the increased energy needs are not met, the horse will start to lose weight.

Other factors that will alter caloric needs are the activity level, housing, and age of the horse. The lean horse in Georgia is probably being ridden regularly and therefore will have higher energy expenditure than the shaggy, overweight horse that is not being exercised, even though the latter is outdoors with only minimal shelter. Horses more than 20 years old have reduced tolerance of weather extremes and will need higher energy intakes than young or middle-aged horses housed under the same conditions at temperatures below their LCT.

Feeding Recommendations

Figure 2. Horses in the winter having access to free choice hay.

In all scenarios during the winter months, horses should be given at least 1.5 to 3% of their body weight in some form of forage, be it in the form of long stem hay, chopped hays, forage-based cubes, or combinations thereof. They should also always have access to salt and unlimited ice-free water. If cold-stressed, the addition of higher calorie supplements such as grain-based concentrates or high fat supplements like rice bran or edible oils may be warranted if the horses cannot maintain weight on forage-based feeds alone. In horses confined to stalls, use of lower energy grass hays will allow for maximal intake and counter not only boredom but may also reduce incidence of gastric ulcers or stereotypical behaviors associated with confinement and stress. If ventilation in the barn is inadequate, use of the higher protein legume (alfalfa or clover) hays should be minimized to prevent adverse air quality issues due to the increased ammonia excretion. Concentrates formulated for the life stage and activity level of the horse can be used but in amounts that consider the reduction in activity.

For horses housed and fed outside in the more severe winter climates, it is strongly recommended that forage be offered in feeders located under a three-sided shelter. Horses kept outdoors will have higher energy requirements and higher energy forages such as alfalfa or clover hay mixed with grass hay can be used. In all cases, horses should be monitored carefully during cold winter months. Early signs of inadequate water or feed intake will be dry, sparse feces, reduced feed intake, increased wood chewing activity, and weight loss. Weight loss can be hard to assess if the horses have long hair coats or are blanketed. Therefore, it is imperative that the ribs and neck be palpated regularly to determine if there is loss of condition.

Supplements

Management and feeding alterations may dictate the need for supplements that would not be required in summer months. Supplementing a poor-quality hay diet with a multi-vitamin/mineral supplement specifically formulated for horses is a good idea during the winter months. However, there are no specific "winter supplement" requirements, and products that claim such benefits are usually overpriced and not necessary. Be sure to carefully evaluate the label claims and avoid products that do not give a complete and specific list of ingredients.

Vitamin and Mineral Supplements

Since lower quality forages are often used in winter to maximize access and intakes, there may be lower intakes of antioxidant vitamins A, E, and C that are lost. Poorer quality hays may also be lower or imbalanced in mineral content relative to the needs of especially young, growing horses and mares in late pregnancy. Therefore, use of a single, balanced multi-vitamin and mineral supplement designed for the type of hay and life stage of the horse may be beneficial.

Figure 3. Alfalfa cubes.

Digestive Aids or Gastric Ulcer Supplements

Horses confined to stalls for prolonged periods of time due to inclement weather may experience psychological stress that can be alleviated in part by provision of free access to forage. However, they could still be at increased risk of gastric ulceration. There is some evidence that use of alfalfa (either long-stem hay or as cubes) as at least part of the ration may reduce the incidence or severity of ulceration, though the environmental concerns mentioned above will need to be addressed. Papaya and other stomach buffering supplements may be given, but research on these products is scarce. Therefore, being an educated consumer in terms of the ingredients or any research that was performed will help in making your decision to purchase the supplement.

Immune Boosting Supplements

These same stressed horses may also have a depleted immune function. Therefore, providing a vitamin E supplement (around 1000 IU/day) will also help decrease stress and increase the immune function during this period.

Calming Aids or B-vitamins

These types of supplements have not been proven in unbiased research trials to be effective in calming a nervous horse. However, B-vitamins are water-soluble, so if a horse has an excess, they will excrete what they do not need in the urine, unlike fat soluble vitamins like vitamin A that are stored in the body and can cause toxicity if in excess.

Anti-Colic Supplements

Usually, these supplements consist of probiotics or yeast cultures, which have never been found to alter digestion in a healthy horse. Usually, the problem of colic in the winter is due to decreased water intake and that can only be remedied by increasing their intake (see the section below for tips on how to increase drinking).

Hoof Supplements

Hoof quality often is adversely affected in winter due to excessively hard or muddy ground and inactivity. Unfortunately, there are no nutritional solutions to this other than insuring adequate protein, energy, and mineral intake. Biotin and other hoof supplements work from the cornet band down and usually take 6 to 12 months to have any effect. If you are trying to treat a brittle, cracked hoof due to weather conditions, you may need to apply something topically. It is best to talk to your farrier about what product would be best.

Figure 4. Frozen water tubs in a horse pasture.

Water

The risk of impaction colic is dramatically increased by inadequate water intake, reduced physical activity, and lower quality forage intake, all of which can be present in cold winter months. Horses will not drink as much ice-cold water as they will if the water is ice free and at least 40 °F. If water is being provided in buckets, it is important that they be checked twice daily and, if the water is starting to freeze, that it be replaced. It is not recommended that electrical bucket heaters be used in stalls in a barn unless they are carefully supervised and insulated due to the risk of fire.

For horses housed outdoors, if waterers are located a significant distance from the available shelter and feed, when there is significant snow/ice accumulation, the horses may not be able to easily access the water source. If water is provided in a stock tank, it is best to have a heater in the tank. If the use of heaters is not an option, you can reduce the chance of the water freezing by insulating the outside with straw held in place with matting or blankets. If the water does freeze, you should break and remove the surface ice at least twice daily when the horses are present and able to drink before it freezes over again. If using automatic waterers with heaters, it is still advisable to check them daily in case a malfunction causes the water to freeze.

Figure 5. Hay cubes being soaked with varying amounts of water.

If you have a horse that will not adequately drink water in the winter, soaking a pound or two of "complete" pelleted or extruded concentrates, beet pulp, or hay cubes in one to two gallons of water before feeding, will increase water intake. A traditional warm "bran mash" made of wheat bran, at least once a week during the winter months, can also be used to increase water intake. However, if wheat bran is included, it is important to realize that it is not a laxative and has a very high phosphorus content that can cause problems if fed in large amounts daily. Other ways to increase water intake are to stimulate thirst using salt, higher protein feeds, and maximizing hay intake. A white salt block should always be available free choice or, for those horses who do not like blocks, a teaspoon of loose salt can be added to their grain ration daily. Higher protein feeds, such as alfalfa hay, and maximizing forage intake (including free choice access) are also effective ways to increase water intake.

Take Home Message

The major nutritional concerns during the winter months include adequate calories to maintain good body condition and adequate water intake to prevent impaction colic. Every situation is different so analyze your horse’s workload, housing and body condition to determine if a change in feed is necessary.