Written By Dr. Kris Hiney

Does the season affect your feeding management? Winter is the season of short days, long cold nights and reduced riding time for us and our horses. Often what we feed our horses in the winter shifts as their energy requirements change, as well as the feedstuffs we might be using. That shift in seasons may mean we need to look at our feed sources and our supplement regimen more closely.

To begin our discussion, remember that a horse’s energy requirements do change with the seasons. Cold weather creates additional caloric demands on the horse’s body in order to regulate its body temperature. When temperatures drop below a certain point, referred to as an animal’s lower critical temperature, it must expend more energy in order to maintain its own body temperature. For horses which are acclimated to cold temperatures (meaning we have allowed them to grow a hair coat and they have been housed outdoors), this lower critical temperature is usually around 5° Fahrenheit. When temperatures drop below this point, we really should be feeding our horses more. In general, for every two degrees drop in temperature, the horse needs 2.5% more calories to maintain its’ body temperature. Therefore, if it gets down to about 10 below, your horse will need 20-25% more feed! These numbers do not consider wind chill factors, which can drive up heat loss substantially. Bottom line, in light of this year’s extreme cold, if your horse is living outside this winter, you may find yourself going through your hay supply much faster than you had anticipated.

How you choose to supply that energy to your horse may be important as well. There are several strategies which may be employed to augment your horse’s calorie deficiency. One easy way to meet energy requirements, along with adding to the heat produced by the process of fermentation in the hindgut, is to simply feed more hay. Consumption of hay has a higher heat increment (or heat associated with digestion) than other feeds, therefore it helps to keep your horse warm at the same time. In addition, more calories can be provided by choosing a higher energy concentrate, such as one with higher concentrations of fat. There are many commercial feeds available with added fat, or choosing rice bran or a flax source may be an option. If choosing a fat-added feed, it will provide more calories to the horse without having to increase as greatly the volume of feed that you are using. Many horse owner’s also like to add warm mashes to their horses diet in the winter. This provides more energy to the horse as bran or pellet mashes are higher in caloric density than forage. The additional benefit is that you can increase your horse’s water consumption, which may have decreased in the winter if they do not have access to heated water. Finally, it just may make you feel good to feed your horse a nice warm mash on those cold days and nights.

Obviously the manner in which we feed our horses also changes with the season. Ideally, horses are allowed opportunities to graze pasture grass in the temperate part of the year. However, with the fall and winter, horses in northern climates much be switched to an all harvested forage diet. While many of the nutrient components in harvested forage may be completely adequate for your horse, realize that the composition of plants does change with advancing maturity. In order to be tall enough to produce hay, grasses and legumes must reach a more mature state than a horse would typically select left to its own devices. In addition, some nutrients, such as vitamin A, do diminish over time. In particular, omega three fatty acids are found in smaller quantities in hay than in fresh growing grass. As we have changed how we manage all of our production animals and switched to more grain based diets, they now consume much more n-6 fatty acids versus n-3 fatty acids than when they were more pastorally raised. In fact, knowledge of the higher content of n-3 fatty acids in grass is in part what has led to the rising consumer popularity of grass fed beef. Grazed cattle consume much more n-3 fatty acids compared to traditionally raised feed lot cattle which have diets much higher in n-6 fatty acids. The diet the animal is on directly influences the n-6 to n-3 fatty acid ratio in their body tissues. Diets higher in n-3 fatty acids have been shown to be anti-carcinogenic, anti-inflammatory and cardio protective. While we may not think about horses in quite the same way, or feed them a concentrate based diet like feed lot cattle, the same process of incorporation of more n-3 fatty acids into their tissues occurs when horses graze or are supplemented with n-3 fatty acids. Ideally, our horses also should be consuming more grass and n-3 fatty acids, and less n-6 fatty acids which are found so abundantly in concentrates. However, even switching to a harvested forage based diet can alter the n-6 to n-3 ratio compared to a fresh grazing. Hay making can result in a loss of fatty acids of more than 50%, especially of linolenic acid, with a comparative increase in n-6 fatty acids. In a study using ewes, grass fed ewes had more milk and tissue n-3 fatty acids than ewes fed a hay diet. But obviously we cannot always feed grass to our horses. Therefore, in order to mimic the natural diet of the horse, and provide them the positive benefits of n-3 fatty acids, we can supplement them in other ways. Flax is a rich source of linolenic acid which horses readily consume. Therefore, in the winter, why not try a flax supplement and at least return your horse’s diet to summer, even if the wind is still howling!