How to calculate your horse's calorie needs?

What is a calorie, and how is it converted to MJ?

A calorie is a unit of energy that indicates how much energy the body can obtain from consuming a particular food or feed. In horse feeding, the value of digestible energy (DE) is key, as it shows how much energy is available to the horse’s body after consuming the feed.

The energy content of horse feeds is usually given in megajoules (MJ), as we are dealing with large quantities. The conversion is straightforward:

• 1 MJ = 239 kcal
• 1 kcal = 0.00418 MJ

Thus, if the energy content of horse feed is listed in MJ on the label, multiplying the value by 239 gives the calorie content.

What is DE, and why is it important?

DE (digestible energy) is the metabolizable energy used to calculate a horse's energy requirements. This value indicates how much energy is utilized after the feed is consumed. On horse feed labels, this value is always provided in MJ/kg. When preparing a feeding plan, this is the primary data to consider.

Example:
Daily Energy Requirement (DE) of a Horse in Moderate Work

Let’s consider a 500 kg horse performing moderate-intensity work. The energy requirement can be calculated as follows:

• Basal Metabolism:
  33.3 kcal/weight kg/day
  $500 \, \text{kg} \times 33.3 = 16,650 \, \text{kcal/day}$

• Moderate Workload:
  $\text{Basal Metabolism} \times 0.5 = 16,650 \times 0.5 = 8,325 \, \text{kcal/day}$

• Total Energy Requirement:
  $16,650 + 8,325 = 24,975 \, \text{kcal/day}$

  In megajoules:
  $\approx 104.5 \, \text{MJ/day}$

Calorie Burn During Exercise

The intensity of exercise affects energy expenditure. For a 500 kg horse:

Energy Content of Feeds

Here is the energy content (DE value) of some popular feeds:

Energy Content of Apples and Carrots

Apples and carrots are common supplements in a horse’s diet. However, they serve more as treats than as substantial energy sources:

Feeding Example

For a 500 kg horse performing moderate work, the daily energy requirement of 24,975 kcal can be met with the following:

• 10 kg meadow hay:
  $10 \, \text{kg} \times 2,100 \, \text{kcal/kg} = 21,000 \, \text{kcal}$

• 1.5 kg Air+Energy:
  $1.5 \, \text{kg} \times 2,820 \, \text{kcal/kg} = 4,230 \, \text{kcal}$

• 30 ml linseed oil:
  $0.1 \, \text{kg} \times 8,700 \, \text{kcal/kg} = 870 \, \text{kcal}$

  Total:
  $25,740 \, \text{kcal}$

  In MJ:
  $\approx 107 \, \text{MJ}$, which meets and even slightly exceeds the daily energy requirement.

Why Use Complex Feeds?

Even if a horse appears to be in good condition or slightly overweight, it doesn’t necessarily mean its body is receiving all the nutrients it needs. Grain-based feeds (such as oats or barley) often lack sufficient vitamins, minerals, and other essential nutrients necessary for optimal health and performance.

Therefore, it is particularly important to incorporate complex horse feeds into the diet. These feeds provide all the vital nutrients and help precisely meet the horse's energy requirements.

Conclusion

Proper feeding not only enhances a horse’s performance but also helps prevent various health issues, such as mineral deficiencies or obesity.

Calculating a horse's energy needs and selecting the right feed are key to maintaining its health and performance. The DE value, provided in MJ on feed labels, is one of the most important pieces of information for creating a balanced diet. Energy supplementation should be provided through diverse feeds tailored to the horse’s specific needs, workload, age, and condition.