Digestible Energy in the equine diet

MAR 19 Horse Nutrition BR Farm
ENERGY: The amount of energy required by a horse for normal bodily functions and changing workload will impact on what feed product is chosen. (FW12-500NN)

CONTROLLING the energy our horses are consuming requires more thought at certain times of the year, but what parts of their diet make up the energy content and how can this impact what feed product we choose? Bluegrass Horse Feeds discuss digestible energy and highlight the key sources of energy found in a horse’s diet.

How much energy does my horse need?

Energy density in a diet is influenced by the amount of energy required by the horse to perform normal bodily functions at a maintenance level. As workload and status changes, the energy demands will also change. The energy source supplied within the diet and level of workload will influence the different metabolic pathways of how energy is produced within the horse. The end product produced is the ATP (adenosine triphosphate) molecule, which is required for muscle activity. ATP is not sufficiently stored within the horse’s body and needs to be re-synthesized at the same time as it’s being used to help maintain performance.

Energy source in horse feed is known as digestible energy (DE) and is measured in Mega Joules per Kilograms (MJ/KG).

Example for 500kg horse:

Maintenance – Require around 70 MJ/Kg per day

Moderate Work – Require around 98 MJ/Kg per day

Where does energy come from?

Fat, fibre and carbohydrates are the main energy sources found in a horse’s diet, protein can provide some energy when supplied in excessive amounts, however this can lead to an increase in water intake and other adverse health effects.

Usually fat is supplied in the diet by oils; fats are digested in the small intestine, but unlike humans, horses do not have a gall bladder, instead bile is continuously secreted to aid the digestion of fats. Oils and fats can supply 2.25 times the energy of carbohydrates and are a great source of slow release energy. Oils are commonly added to performance feeds to improve stamina, allowing the horse to save glycogen stores when the exercise intensity increases, known as “glycogen sparing”.

Different types of fibre sources will have different nutritional impacts on the horse. Fibre is digested in the hind gut via microbial fermentation, breaking down the fibrous content into volatile fatty acids, which are absorbed into the blood stream and utilised as energy. Fibre is a slow release energy source and should be the base to any equine diet.

Fibre is known as a structural carbohydrate, Cellulose is the most and abundant and is made up of glucose molecules but require the microbiome population to break down these bonds. Non-structural carbohydrates, also known as water soluble carbohydrates, are soluble in water for gut fluid. The most common water soluble carbohydrate within horse feed is starch; starch is broken down into the disaccharide, maltose by the enzyme, amylase. However, within horses, amylase production is restricted and therefore large undigested starch meals can move into the large intestine causing issues, such as hind gut acidosis.

When choosing a feed product for your horse, firstly look at the overall diet and desirable energy requirements. Consider the cooking techniques of cereals, as this will impact the digestibility and ultimately bioavailability within the horse. You can speak to one of our expert nutritional advisors at Bluegrass Horse Feed for the advice on the most suitable energy sources for your horse and help developing a tailored diet plan.

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