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“Cold” appears relative to the individual. In my house the winter thermostat setting of 65°F is comfortable, but others voice that’s too cold and the setting should be 72°F. In my experiences with raising horses in Virginia, cold was when the thermometer read below 35°F; however in California the threshold appeared to be higher in which I would hear disgruntled comments when temperatures dropped below 50°F. Experiences, and perhaps the lack of experiences, are why there is a diverse sense of what is cold for a horse and thus the differences I see when concerns evolve around managing horses during winter. So, what should be the focus?
Once the temperature sinks below 45°F the horse’s body begins to utilize more energy in order to maintain body temperature. Hair coat, body condition score (BCS), moisture and wind chill factor are also considerations that will influence the horse’s energy expenditures during the cold winter temperatures. A horse that is allowed to develop a winter hair coat and gain weight for a higher body condition score will be in a better position to manage winter challenges. The longer hair coat and additional body weight provide insulation and the added body weight can also serve as an energy reserve during the colder time periods.
For the average horse owner feeding management during the cold weather perhaps depends more on nutritional management skills then science. The primary goal is to maintain an appropriate BCS. There are estimates from studies that appear interesting but for most these science driven tips are difficult to apply. For example, “…for each 1°F decrease below 45°F, the horse requires a 1% increase in digestible energy to maintain a consistent body temperature”. So do you know what and how much to add the diet if the temperature is 38°F? The math to make this calculation is at the end of this fact sheet.
The practical approach is to watch body weight; specifically, evaluate BCS weekly and begin implementing nutritional management insurances prior to winter. For example, as the cold season approaches, and since reliable weather forecasts are readily available, a horse owner should be making adjustments to their horse’s diet and management prior to the cold season and before the drop of temperature begins. Cautionary note regarding BCS: most horse owners develop a visual perspective with the BCS system but the system is actually based on manual inspection of fat deposition with 10 external body parts. A long hair winter coat can easily obscure a true BCS so a manual inspection is essential. Visit Body Condition Scoring in Dr. Bray’s Corner for written and video guidance.
The fundamentals with feeding management really do not change, they just need attention. Free access to water is always critical. And during the winter, attention to water temperature is equally critical. Most horse owners understand that when water is really cold or warm, the horse drinks less. Drinking water temperature should be between 45° and 65° F. During colder temperatures, a horse’s water consumption will decrease most likely because he or she is less active, does not have the challenges of temperatures from heat, if pastured consumes less high moisture grasses, and does not relish drinking very cold water. Less water consumed results in a higher risk of colic episodes.
Obviously water is critical to maintaining hydration and fluid balance in tissues. But water also serves as a lubricant, which is a medium for digesta (food being digested) transport in the gut. Although during the winter a horse that has free access to water may not appear dehydrated, they could be. For a lack of a better expression, the phrase “subclinical dehydration” is a reasonable depiction. This means the horse will drink enough water to fulfill the thirst craving but not the volume that is adequate to hydrate body tissues. Think about it: Have you tried drinking ice cold water on a freezing day? Have you drank water that has been sitting in a hot car all day when it’s 105°F?
Less water consumption translates to less water to hydrate body tissues as well as less water in the gut. This is a reminder that water volume is vital to a healthy functioning gut. So how does one control water temperature? There are commercially available water heaters including solar heaters. Obviously if an electrical source is used, access to power that the meets all electrical codes is critical. This horseman can recall his own experience with an inadequate ground to a pasture water trough heater. When water temperature nears freezing, estimates have been reported that the average 1100 lb horse will drink 1 to 3 gallon less per day.
Adequate fiber is also important to maintain gut integrity. The fact sheet on forage feeding recommendations, Feeding Guidelines for Horses, covers this in detail. Long stem fiber promotes the gut to move with more vigor and also requires the horse to drink more water. Winter nutritional management for your horse should include feeding long stem fiber (hay from the bale) and the added forage amount will vary with the environmental temperature, horse activity and hay source. Usually start with an increase of about 10%. So if a 1100 lb horse is fed 1.5% of body weight (= 16.5 lbs of hay) then 10% increase of the 16.5 lbs being fed is a little more 1½ lbs (actually 1.6 lbs) added per day. Long stem fiber requires a horse’s gut to contract and the increase in gut motility parallels the increase fermentation of the fiber and an increase in cellular metabolism to utilize the energy source produced by the gut’s bacteria. The combination of these digested processes is what generates the added body heat that can be used for body warmth during the cold.
Grains, such as corn, oats and barley, are highly digestible feeds but do not produce significant amounts of body heat during the digestive process. If the horse does not maintain body weight with added forage during winter months, then balanced formulas that contain more energy dense feedstuffs, such as fat (oil) rice bran or grains should be considered. But you still need to feed the extra forage for generating that internal body heat.
There are those who feel a thick blanket is needed but winter blankets will reduce the hair coat development and there are obvious risks for injury. Bottom Line – Well-fed horses adapt reasonably well to cold weather, whereas underfed horses will lose weight, lose body condition and thus have less cold tolerance.
A Few Cold-Weather Management Tips
- Listen to weather forecasts and make plans in advance for cold periods.
- Begin increasing the amount of long stem hay fed approximately 72 hours prior to cold conditions and maintain the level determined during the cold period; a 10% increase should be the initial target. Review Feeding Guidelines for Horses in Dr. Bray’s Corner for feed adjustment guidelines.
- Allow your horse to carry extra body weight during the winter; for example, if the ideal BCS for your horse is 5.5 then allow weight gain for a BCS of 6.0.
- If the horse has difficulty maintaining body weight during winter, then not only increase long stem forage intake but also increase the concentrate intake.
- Use a fat source (oil or rice bran) to increase the energy density of the balance formula feed if needed to maintain body weight.
- If the water source is not heated then offer warmed water daily; up to 10 gallons per day.
Advanced: “Doing the Math”
“…for each 1°F decrease below 45°F, the horse requires a 1% increase in digestible energy to maintain a consistent body temperature.”
Question: 1100 lb gelding and the temperature for the upcoming week will approximately 38°F
Background Information: Hint – Information that you would need to know
- The 1100 lb gelding is not very active and is consuming 17 lbs of a Bermuda grass hay and 2 ¼ lbs of Integrity Lite
- Total feed intake (19¼ lbs) provides 16.7 Mcal of Digestible Energy (DE); 14.5 Mcal DE is from the Bermuda grass hay and 2.2 Mcal DE is from Integrity Lite
- According to the science-driven tip, for each “1°F decrease below 45°F, the horse requires a 1% increase in digestible energy
- 45°F – 38°F = 7°F
- Therefore for a 7°F decrease there will be a 7% increase in digestible energy
- 7% of 16.7 Mcal equals 1.2 Mcal (0.07 X 16.7 = 1.17 or round off to 1.2)
- 1.2 Mcal DE can be provided by:
- approximately 1.4 lbs of the Bermuda grass hay
- or a little more than one lb of Integrity Lite (approximately 1.1 lb)
- Since long stem hay increases gut motility, there will be an increase in body heat generated. Therefore one should feed the additional hay.
- For 38°F, a 7°F temperature below 45°F, the horse should be fed 18.4 lbs of hay and 2 ¼ lbs of Integrity Lite
- If body weight is not maintain, then add 1/3 cup oil or ½ cup of Integrity Rice Bran for addition energy and observe BCS
So, how’s that math working for ya?