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  • Writer's pictureHolly Heartz

Understanding How to Feed Your Horse

How we feed our horses is a practice that is often passed down through the generations. One may learn from their parents, if they owned horses, or their coach who learned from someone in their past. 

The science of nutrition is a relatively new field of study. Much of what we know comes from human nutrition studies. Nutritional needs of the equine are not much different, yet methods of feeding have not changed with new information.


The major component of your horse’s diet should be forage, e.g., hays or pasture. Sometimes, this is all the horse needs - no supplements or grains required. To determine if a supplemental feed is required, you first need to know nutrients the horse is consuming in their forage. This is the same for people. Diets are analyzed to determine what, if any, macronutrients, vitamins, or minerals are deficient.  Providing multivitamins generally causes no ill effect as the amounts of supplements contain are not high enough to cause health issues. Problems can arise when individual nutrients are provided, as certain nutrients can impede the absorption of other nutrients leading to deficiencies.


The four main energy sources (macronutrients) required include:

·         Glucose – little processing is required and it’s easily used for energy.

o   Fermentable fibre (cellulose, hemicellulose, pectins) – this is not digestible and requires microbial fermentation to provide the energy source

o   Hydrolyzable carbohydrate (starch and simple sugars) – this is digestible

·         Fats and oils – these are a concentrated energy source but energy generation is low.

·         Protein – these are broken down into amino acids. The body prefers not to use protein as an energy source. Protein will be used for energy when the horse is starving and glucose is in short supply.

How many calories does your horse need?

The calories, or energy, your horse needs to eat in a day will depend on several factors: breeding, pregnancy or lactation, growth, age, body condition score, environmental conditions, exercise or activity level, and deficiencies. I’ll focus on the maintenance of an adult’s weight. Using a weight tape or using a body condition scoring system can achieve the goal of whether your horse should be maintained at their current weight.  If the horse maintains a score of around 5, on the Henneke body scoring system, then the calories being consumed is sufficient. It does not tell you if the form of those calories (macro and micronutrients) is in amounts your horse requires. The next step will be to figure out how much of the other nutrients in the forage is available to the horse. That will be for another blog.

How much does the horse weigh?

Knowing how many calories the horse is eating can be difficult unless you’re portioning out or weight the amount of hay being provided. The current recommendation (NRC) is that adult horses should get 1.5-2.0% per kg of body weight. 

To measure the horse’s body weight, you will need a weight tape. This is the tape I use.

Instructions on how to use the tape can be seen here

Estimating body weight using age, heart girth and body length can be acquired using a calculator which is located further down on this page

How much is the horse eating?

A sample of the forage is required to be analyzed to identify the nutrients available to the horse.  Ideally, take a sample from the center of the bale. This can be sent to an Agricultural Center for analysis.  Some veterinary universities may do analysis too. The organization will provide the analysis results which includes calories and various nutrients. The nutrients listed may depend on what you check off on the order form.

The results can be used to figure out how many calories the horse is consuming. If the horse is on pasture, you likely don’t know how much is being eaten. In this case, you can do an estimate as an average 1000 lb (454 kg) horse typically consumes 9 kg (20 pounds) of forage—grass and hay—per day. 


Reference the Nutrient Requirement of Horses (NRC)

The tables in the NRC are guides to the horse’s energy requirements. It provides us with the amount of digestible energy (DE) horses need for various weights and other conditions as listed above. DE is measured in megacalories (Mcal), which is 1000 kilocalories, and will be listed on the hay analysis as Mcal/kg or Mcal/lb. The tables in the NRC provide a range of energy at various activity rates.

The Story of Rooster and My Need to Get His Calories Right

Let me tell you about my boy, Rooster, a draft mix breed. He is the horse on the left in the top image. I purchased him a few years ago. I didn’t have a veterinarian check him beforehand as I was a bit desperate to get a herd mate for my mare, whom I plan to move to my property. She was boarded at a barn where her needs weren’t being met. Rooster may have been a bit overweight but seeing that he was part draft I overlooked this and stacked it up to his breed…and the fact that he was short. I would look thinner if I was a few inches taller too.


My horses have free access to their paddock and barn and there are no stalls in the barn. Also, they have free access to hay.  They did not have access to grass. Despite their living arrangements, Rooster became laminitic (for more on laminitis, see this article in The Horse).  Admittedly, he likely gained a few hundred pounds. He was assessed by the veterinarian, had x-rays of his feet, and bloodwork. Rooster was diagnosed with Metabolic Syndrome. 


The veterinarian prescribed Metformin to help control his elevated insulin levels, and recommended reduced food intake for weight loss. I did a calculation to find out how much have Rooster could have daily and I found a feed which was low in sugars for some extra nutrients which were missing from his diet.


Additionally, Rooster is extremely food driven and I could foresee behavioural issues arising and a stressed horse.  Not good for an already compromised boy. 


At first, Rooster was just sore, but it progressed to lying down all the time.  He was able to get up but not without severe pain. I cannot express my devastation at seeing my boy in such distress. I cried and felt sick to my stomach thinking that I may have to put him out of his misery. I was determined to find answers and delved deeper into study on nutrition and hoof care.


I went through a few different trimmers, and I was able to find someone who could see to his hooves appropriately. Working with the veterinarian, we were able to find the right medication combination, and I was able to be more lenient with his intake so he would be satisfied with his food and not try and take the other horses’ food.


In what seemed like a short amount of time, dare I say days, Rooster was up and moving.  He progressed to running, even jumping and kicking.  He seems friskier…something I’ve never seen since I brought him home.


I had my Rooster back.




NRC. Nutrient requirements of horses. 6th edition. Washington, DC: The National Academies Press; 2007.

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