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DE – Digestible Energy in Horse Feed

What is DE and Why Does It Matter?

DE is important because:

  1. It helps determine how much feed a horse needs to maintain weight and energy levels

  2. It allows owners to balance energy intake with workload

  3. It enables comparison between feeds based on energy content

  4. It’s a common measurement shown on feed bags. 

Measuring DE (Digestible Energy)

DE tells you how much energy from feed is digestible, but not how fast it’s delivered.

DE vs GI

While DE and GI are both related to feed utilisation, they measure different things:

  • DE: Total digestible energy from all nutrients (protein, fat, carbohydrates)

  • GI: How quickly carbohydrates are digested and raise blood glucose

👉 A feed can have high DE but low GI if its energy comes from fibre and fat - ideal for horses with metabolic concerns or those needing slow-release energy.

How DE is Calculated

DE is the amount of energy that can be digested and absorbed by the horse’s system. It’s calculated by subtracting energy lost in faeces from total feed energy.

How to use DE values when selecting and managing horse feed

Units of Measurement

DE is measured in:

  • MJ/kg (megajoules per kilogram – metric standard)

  • Occasionally: Mcal/kg or Mcal/lb (imperial)

Conversion note:

  • 1 Mcal = 4.184 MJ

  • 1 lb = 0.4536 kg

Here's how to use these values:

First, consider your horse's energy requirements, which vary based on:

  •  Body weight

  • Activity level (maintenance, light work, heavy work, breeding, growing)

  • Environmental conditions (cold weather requires more energy)

  • Age and health status

Daily Digestible Energy Needs

A 500 kg horse typically needs:

  • Maintenance:
     16.4 Mcal/day = 68.6 MJ/day

  • Moderate work:
     20–25 Mcal/day = 83.7–104.6 MJ/day

How to Use DE Values

1. Forage (60–100% of diet)

  • Grass hay: 1.8–2.2 Mcal/kg = 7.5–9.2 MJ/kg

  • Alfalfa hay: 2.2–2.5 Mcal/kg = 9.2–10.5 MJ/kg

2. Concentrates (grains/commercial feed)

  • Most commercial feeds: 2.5–3.5 Mcal/kg = 10.5–14.6 MJ/kg

Example:
 If your horse needs 20 Mcal/day (83.7 MJ)
and your hay provides 2.0 Mcal/kg (8.4 MJ/kg)
→ you need 8 kg of hay
→ plus some concentrate to meet the rest of the requirement.

Common Mistakes to Avoid

❌ Don’t choose feed only by DE value
 ❌ High DE doesn’t always mean high quality
 ✅ Always consider forage when calculating total energy

Feeding Forage and Concentrate Together

Forage (such as hay or pasture) should form the foundation of a horse's diet, making up at least 50% or more of their total daily intake by weight. Concentrate feeds, like Fiskens Ultra Low GI, are designed to complement, not replace, forage. They provide additional digestible energy and nutrients where forage alone cannot meet the horse’s full requirements, particularly for horses in work, growing horses or those with special needs.

Even when feeding a highly digestible, low-GI concentrate, maintaining a strong forage base is crucial for digestive health, behavioural well-being and metabolic stability.

Forage & GI (Glycaemic Index)

Forage like hay and grass generally has low GI because of:

  • High fibre content

  • Slow digestion

  • Complex carbohydrates

  • Lower sugar than grains

Forage GI Varies With:

  1. Time of day grass is cut (afternoon = higher sugar)

  2. Season (spring grass = higher sugar)

  3. Plant maturity at harvest

  4. Type of hay (legumes like alfalfa = higher GI)

  5. Storage and curing

For horses prone to laminitis or insulin resistance, test forage for sugar and starch - don’t rely on appearance.

DE of Fiskens Ultra Low GI  

Our Ultra Low GI Horse Feed has a DE of 11.6 Mj.kg. 

The typical digestible energy ideal range for performance horse feeds is 10.46 to 12.55 MJ/kg - to provide sufficient energy density for horses in work, training or competition.

The DE for our horse feeds is on this website and is printed on our feed bags.

Fiskens Nutritional Science

Fiskens feeds are formulated in collaboration with qualified equine nutritionists for optimal performance and balance. With over 60 years of expertise in equine nutrition, Fiskens is a trusted leader in developing scientifically-backed feed solutions that support horse health and performance across all disciplines.

Superior nutrition that won't break the bank!

 

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