by: Kimberly Peterson, DVM
February 01 2008, Article # 11409
Cold and inclement weather conditions present special challenges for the horse. Whether a horse is turned out or exercised regularly, you need to be focused on the nutritional requirements of your fuzzy, four-legged friend. Horses are naturally well-adapted to thrive in frigid weather if they have the basics of adequate calorie intake, palatable water, and protection from wind and severe precipitation.
It is important to take into consideration any additional stress factors when assessing the caloric needs of your horse. Other calorie-burning conditions, such as late gestation, chronic pain, metabolic diseases, contagious illness, or parasite infestation, significantly increase the body's demand for calories. Frequent assessment of physical and environmental conditions is necessary to maintain optimum body condition.
Before severe weather sets in, your horse needs a physical examination, including a dental exam and current immunizations and deworming. Consider asking your veterinarian to check a complete blood count and blood chemistry panel to rule out any underlying conditions that add stress to the horse.
You will encounter several calorie units throughout equine literature. A calorie (c) is the amount of energy it takes to raise one gram of water one degree Celsius. A Calorie (C) represents the amount of energy it takes to raise one kilogram (1,000 grams) of water one degree Celsius. The Calorie, also called a kilocalorie (Kcal), is the unit of measure used in human nutrition. A megacalorie (Mcal) is 1,000 kilocalories. Megacalorie (Mcal) is the unit used to measure energy in equine and other large animal diets.
Generally, horses at rest in ambient temperatures of 70°F consume 2% of their body weight in roughage (hay) per day. A 1,100-pound horse will eat approximately 22 pounds of hay per day. Assuming an energy density of 1.0 Mcal/lb, which is typical of many hays, this equates to approximately 22 Mcal or 22,000 Kcal.
Roughage in the diet is the main source of heat for the horse. The bacterial fermentation of fiber in roughage, occurring in the large intestine, results in the majority of heat produced during digestion. Horses unable to consume enough hay to maintain body condition might be supplemented with grains and oils. Many horses do very well on a diet of 100% hay and should always have at least 50% of the diet as hay. Sick horses or those at increasing levels of exercise or illness might consume more calories with the addition of cereal grains (oats, barley, rye, wheat, rice, and corn).