Demystifying Digestible Energy

Digestible Energy (DE) refers to the amount of energy (calories) that a particular feed or forage will supply. The digestible energy requirements will vary depending on the individual horse and what they require for maintenance, as well as what they might require for workload and a correct body condition. In horse feed, the measure of energy is in ‘mega joules’ and is typically listed on the back of a bag of feed for every kilogram that is being fed (Mj/kg).

How much energy does my horse require?

The easiest way to establish whether your horse’s diet is supplying enough energy is to assess their body condition. Energy and calories are the same thing, and so the amount of digestible energy that a feed will supply is also an indicator of how ‘conditioning,’ a feed might be. For example, a feed with a DE of 12.5MJ/kg would typically suggest that it is a feed that will supply a higher amount of energy and is often seen in conditioning feeds. A feed with a lower DE (such as 8-9MJ/kg) would be suited to a horse who does not require a higher volume of calories in order to maintain their weight. If your horse is in good body condition, it is likely that they are consuming the right amount of energy. Similarly, if your horse is overweight they will be receiving too much energy, and an underweight horse will require more energy.

The National Research Council has provided the below estimated energy requirements for a horse per day, depending on their exercise level alone. However, it is important to reiterate that every horse is different and their calorie requirements will vary on an individual basis.

Concentrate feed is not always to blame!

It can be very easy to blame the concentrate feed for excess energy or weight gain due to an oversupply of calories, however this is not always the case. As you will see from the graph below, the DE of hay is an important factor to consider, particularly if you are managing a good doer who is overweight. In 2023, the average DE for forage that was analysed by Saracen Horse Feeds is approximately 9.9Mj/kg. Hay of course will be fed in much higher quantities, and so a 500kg horse having 7.5kg of hay will be receiving 74.25MJ/kg from their forage alone. This is already higher than the suggested amount required for maintenance as outlined by the NRC above.

Forage can of course be highly variable, and grass in particular can differ based upon the plant species, weather conditions and time of year. Grass is naturally high in sugar, and this is more often the case during the spring and autumn months, with sugar being upwards of 20% in spring grass. These sugars are absorbed into the bloodstream quickly and give the horse instant-energy. Some horses, for example good-doers, tend to use this extra energy for weight gain, whereas others will use this energy as excitable or spooky behaviour. If your horse has previously been performing well and sharp or reactive behaviours start to arise, it is important to consider any changes to their forage or management, as well as the possibility of behaviour related to pain. Similarly, if your horse is on a low-calorie feed such as a balancer and they are still gaining weight, it is more than likely that the forage will need to be addressed. Soaking hay, strip grazing or muzzling can all be highly beneficial in reducing overall intakes. Note : It is important that a horse receives no less than 1.5% of their body weight in forage on a dry matter basis per day.

NEED FURTHER GUIDANCE?

If you are unsure on how much energy (calories) your horse might require and what a suitable feed recommendation might be for them, please call our nutritional team on 01622 718487.