Carey A. Williams, Ph.D. Associate Extension Specialists, Department of Animal Sciences
Sarah Ralston, VMD, Ph.D., DACVN, Associate Professor, Department of Animal Sciences
Fact Sheet #1143 – Published February 2011
Winter conditions vary dramatically between the various regions, as do the tolerances of individual horses to cold weather stressors, so 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 concerns) 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 as well as giving some basic feeding recommendations and dispelling some common myths regarding feeding horses in winter.
In 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 discomfort for multiple days (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, temperature below which the horse will start to use more energy for maintaining body warmth than their normal expenditure) the caloric needs will generally 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 50ºF, where a shaggy, overweight horse accustomed to living outdoors with only three-sided run-in sheds in Minnesota may have a LCT of 30ºF or lower. If a horse is shivering it is a good indication that it’s LCT has been reached. Piloerection, or 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 are in need of 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 over 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.
In all scenarios, in winter months horses should be given at least 1.5 to 3% of their body weight in some form of forage; it could be in the form of long stem hay, chopped hays, forage based cubes, or combinations thereof. They should also have access to salt at all times 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 take into account the reduction in activity.
For horses housed and fed outside in the more severe winter climates, it is strongly recommended that forages be offered in feeders located under a three-sided shelter. Horses kept outdoors will have higher energy requirements and the 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/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.
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 over priced 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 in order to maximize access and intakes, there may be lower intakes of anti-oxidant vitamins A, E and C that are lost in prolonged storage. 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.
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 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
Stressed horses may also have reduced immune function. Therefore, providing a vitamin E supplement (around 1000 IU/day) and Vitamin C (0.01 gm/kg body weight twice a day) may help decrease the adverse effects of stress during prolonged confinement.
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 don’t need in the urine, unlike fat soluble vitamins like vitamin A that are stored in the body and can cause toxicity if in excess.
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 (for tips here, see the section below).
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 3 to 6 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 and it is best to talk to your farrier about what product would be best.
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 40ºF. 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 of the tank 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 necessary to check them daily in case a malfunction causes the water to freeze or is generating stray electricity. If you have a horse that will not drink adequate amounts of 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 once or twice a day 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 on a daily basis. Other ways to increase water intake are to stimulate thirst by the use of salt, higher protein feeds, and maximizing hay intake. A white salt block should be available free choice at all times or, for those horses who do not use the blocks, a teaspoon of loose salt can be added to their concentrate ration daily. Giving unlimited access to forage is also a good way to increase water intake as long as there is free access to unfrozen water.
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.
Published: February 2011
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