With Shannon Pratt-Phillips, Ph,D

 November/December 2015


Q: Do  I  need  to  feed  my  horse  more  in  the  winter?


Additional hay in the winter can provide two things for your horse - calories to help fuel him so he can withstand colder temperatures, and fibre, which, when fermented in the horse's large intestine, also provides heat.

Horses produce body heat by shivering and conserve heat through vasoconstriction (constriction of blood vessels) and piloerection (when body hair stands on end). This requires additional calories, or the horse will use its own reserves and eventually lose weight, which often happens in the winter if you don't feed more. Hay has calories, and is safe to feed free choice or just more of it, unlike grain.

When feeds are digested by the horse, it is an inefficient process, where energy is lost as heat. This heat increment of feeding, that is, the heat energy lost during digestion and fermentation, is highest in feeds that are high in fibre (forages, beet pulp, etc). Therefore, giving your horse some additional hay, or even straw, in winter provides additional fibre that can create a bit of an internal furnace for your horse. Straw is excellent in this regard, but you should make sure your horse has good teeth and chews straw properly before you feed it to avoid any

Horses require more forage in the form of hay or straw-in cold weather, to maintain their core body temperature.

risk of impaction colic. He should not drop any of his feed as he chews (called quidding), should appear to chew evenly with both sides of the jaw and should not make any abnormal movement in his head as he swallows.

In general, I recommend at least one extra flake per day of hay during the winter, and two to three extras (and perhaps some straw) on colder days. Provided a horse is in good body condition (not overweight), however, I prefer offering horses hay free choice, so they can eat what they need to maintain overall energy balance with the additional calories to keep them warm.

Q: Should  I  feed  bran  mash  as  a  winter  treat?


Bran mash does not have any nutritional or digestive health benefits over other treats - in the winter or summer. It has been traditionally offered to horses once a week as both a treat and a gentle laxative. Research has shown, however, that bran mash does not technically create a laxative effect, in which it should draw water into the digesta to move things through along.

A warm bran mash can give the horse some momentary warmth and some additional fibre and may also be a way to sneak in some additional salt, but so could hay cubes soaked in warm water.

When fed infrequently (such as once a week), bran mash can disrupt the microbial organisms within the horse's large intestine. These microbes, that build an ecosystem based on the horse's regular diet, are extremely sensitive to changes in diet and weekly bran mash may, in fact, do more harm than good. The offering of a weekly treat may disrupt the ecosystem enough to cause digestive issues, such as colic.

If you want to offer warm bran mash over winter, I would encourage you to do so daily, but with a few precautions. Feeding bran mash daily could be a way to add in some extra calories, fibre and even protein over the winter months, but you may need to watch those calories if you have a horse that is already in good condition and particularly one that is "over conditioned" - aka overweight or fat.

Bran mash is no more nutritious than any other treat, and feeding it only occasionally can upset your horse's digestive tract.

The calcium to phosphorus ratio in wheat bran, however, is VERY misbalanced. Ideally, the diet should contain approximately two parts calcium for every one part phosphorus. The Ca:P ratio in wheat bran is closer to 1:6! Therefore, it is very important to work with a nutritionist who can recommend some other feeds, or supplemental calcium sources, to bring the Ca:P ratio of your horse's diet back into balance.

So, if you want to add bran to your horse's diet, do so carefully. If you're truly looking for a warm treat, you could just use warm water over his daily concentrate (grain or commercial mix), particularly if you're feeding a pelleted feed (these soak up water well). If you're just looking for treats, apples and carrots are a time tested favorite and, because they are mostly water, they don't usually cause many digestive issues.

Q: Should  I  warm  my  horse's  water  when  it's  cold  outside?


Water is the most important nutrient a horse needs, and that is often overlooked, particularly in winter. Winter colic can be due to an impaction of dry digesta (partially digested food) within the gastrointestinal tract, which may be caused by dehydration from decreased water intake.

Research has found that horses prefer water when it is 10°C, but as long as it is warmed above freezing, a little colder water shouldn't deter drinking.

The biggest factor in water temperature will likely be your facilities and management. A heated water bucket is sufficient inside, and these are economical and efficient. Using buckets also provides a way for you to monitor your horse's water intake daily (vs using automatic waterers). They do, however, require more work to fill daily, and this can be an arduous task in the winter!

Thirst is regulated by sodium in the blood (the Na of the NaCl/sodium chloride of salt), so you want to make sure your horse is getting plenty of salt. This can be given loose (about two tablespoons added to the feed), or fed via a salt block or commercially manufactured feeds with salt already added. Feeding another tablespoon per day in the winter to help stimulate drinking shouldn't hurt (provided your horse does have access to unfrozen water and has healthy kidneys). You can also add water to his feed, mixing it with your commercial feed or some hay cubes - as long as it doesn't freeze (a second heated bucket can help here).

Snow and ice are not suitable for horses to sustain their water requirements even when a horse is kept outside in the winter. 

A heated water hose helps facilitate refilling troughs, and while a heated water trough (>$300) or high quality water heater (>$100) may be expensive, they can save on labour and vet bills in the long run. 

A heated water trough or submergible water heater is well-worth the investment during the winter months.