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Considerations on How to Supplement Horses Diets: Part One


The considerations on how to supplement horses’ diets are extensive. Therefore, trying to fit them into a single blog that is reader friendly would just not do the topic justice. As such, we will cover this across a two-part blog series.

In Part One (this article), we will cover the following questions:

  • What is a horse supplement?
  • Should you give your horse supplements?
  • Do horse supplements really work?
  • How long does it take horse supplements to work?

In Part Two (the next article – coming soon), we will then look at:

  • What do different supplements do for horses?
  • How should you start a horse on supplements?
  • What to mix with horse supplements?
  • What horse supplements should not be mixed?
  • How many supplements is too much for a horse?
  • Why are supplements important for horses?

This article has an approximate read time of 13 minutes. So get comfortable and let’s get started.


Firstly, it may be interesting to note that when it comes to EU animal feed regulations that formally there is no such thing as a “supplement”.

Instead, there are different categories of “animal feeding stuffs” referenced, such as “feed materials” and “feed additives”. “Complementary feeds” are then a blend of two or more feed materials. The equestrian industry commonly refers to these feed categories as “supplements”. Because of this widely adopted term, we will continue use the term supplements for the majority of this article.

So, whilst the word supplement doesn’t appear in the EU feed regulations, it is of course a word. The definition of supplement as a noun in the Cambridge Dictionary [2024] is given as:

“something that is added to something else in order to improve it or complete it; something extra:

 With a Thesaurus synonym, antonym, and example of:

something that is added

  • addition: Blueberries make a delicious addition to your smoothies.”

 Secondly, if we then look at the different categories of animal feeding stuffs, we can see that according to European Commission (EC) regulations:

  • “‘feed’ is any substance or product, including additives, whether processed, partially processed, or unprocessed, intended to be used for oral feeding to animals”.
  •  “‘feed materials’: products of vegetable or animal origin, whose principal purpose is to meet animals’ nutritional needs, in their natural state, fresh or preserved, and products derived from the industrial processing thereof, and organic or inorganic substances, whether or not containing feed additives, which are intended for use in oral animal-feeding either directly as such, or after processing, or in the preparation of compound feed, or as carrier of premixtures”.

 In addition to which, according to the EC:

  • “Feed additives are products used in animal nutrition for purposes of improving the quality of feed and the quality of food from animal origin, or to improve the animals’ performance and health, e.g. providing enhanced digestibility of the feed materials.”

 Importantly though, these should not be confused with:

  • veterinary medicinal products (VMPs), which are substances, or combination of substances, for disease treatment or prevention for example.
  • or medicated feeding stuffs, which are VMPs mixed with other feeds.

Therefore, we can derive that the intention and definition of supplements for horses (also known as equine supplements) is:

Something extra (non-medicinal) that is added to the horse’s diet orally to improve or complete it nutritionally, whilst meeting the nutritional needs of the horse and/or to improve the performance and health of the horse.

Derived definition of a horse supplement


Supplements for horses can be an emotive topic, with strong opinions present at both ends of the spectrum. As with most things in life, a balanced approach is likely to lead to the best path. In addition to which, the horse should be considered as an individual. The outcome of which may be to not supplement, or to supplement. If the latter, then its about being discerning in what is selected. Either way, a logical thought process can be followed. Therefore, giving peace of mind that the decision reached is based on horse centric information, as is available to you.

With that in mind, we would say that the person responsible for the horse could consider taking the following approach to reach the decision that is appropriate for that horse:

  1. Assess the existing diet ration and whether it fully meets the nutritional needs of the horse, or not, considering the following:

    • Due to the gastrointestinal tract of the horse this diet ration should have a forage basis and the quantity, quality and nutritional analysis of this forage be known. In this instance forage is being referred to here as grass, hay or haylage.
    • The presence of a bucket (or hard) feed (e.g., concentrate feed) and the nutritional analysis of this also referenced.
    • Whether support from an equine nutritionist is required to help with this assessment.
    • The age, gender, life stage (e.g., pregnant, lactating, breeding), body weight and body condition score of the horse.
    • Whether the horse needs to maintain, reduce, or increase body weight and/or condition score.
    • Health status of the horse (e.g., healthy with no known conditions, or has a professionally diagnosed condition). In the case of suspected health conditions, then advise from your veterinary surgeon to be sought over self-diagnosing.
    • Any veterinary advice and guidance (e.g., due to health conditions, or during periods of rehabilitation).
    • The workload of the horse (e.g., maintenance, light, moderate, intense) and related energy demands.
    • Additional discipline specific performance demands placed on the horse.
  1. Identify whether any adjustments to the forage and bucket feed could / should be made to balance it better according to the needs of the horse, which could involve one or more of the following actions:

    • Removal (e.g., bran if overall diet is already too high in phosphorus).
    • Addition of feed items (e.g., sugar beet to increase energy with highly digestible fibre).
    • Avoidance (e.g., opting for horse feed low in sugar and starch for a horse dealing with laminitis, avoiding those with high values).
    • Substituting (e.g., changing the horse from hay to haylage, or vice versa, because of energy needs).
  1. Once the basis of your horse’s feed is confirmed, then you can determine what is:

    • Over-supplied in the diet ration and if there are any upper limit concerns. For example, Iron (Fe) is usually present in higher than desirable amounts in forage in the UK and Ireland, meaning that additional inclusion of Iron through other sources is often undesirable.
    • Under-supplied in the diet ration and what impact that might have. For example, Lysine, an essential amino acid, is often in short supply in forage meaning that it may need to be added to the horse’s diet from an additional source.
    • Missing from the diet ration. For example, Silicon (Si) is an abundant mineral but is often not available in a suitably bioavailable form.
    • The actual ratio compared to the required ratios of minerals and limiting amino acids for the horse, for example: Calcium : Phosphorous (Ca : P), Calcium : Magnesium (Ca : Mg), Iron : Copper : Zinc : Magnesium (Fe : Cu : Zn : Mg), Lysine: Threonine: Methionine.
    • Then look at the resultant output in relation to lower and upper safe limits / ratios and minimum requirements.
    • Under demand in your horse due to health and performance requirements (e.g., is the equine connective tissue system being impacted upon due to wear and tear with age, box rest or because of moderate/intense work).
  1. Decide on next steps, which could be:

    • Do nothing: the horse’s diet covers what is needed and no additional supplementation is required.
    • Take action: select a supplement for horses (or supplements) to help bridge the gaps in the diet for the horse’s own unique situation.

As we are sure you appreciate, this process flow means that there is not necessarily a one-size fits all approach and it will very much depend upon you and your horse’s own specific situation as to whether you should give your horse supplements or not.

<img src="processflow.png" alt="">
Process flow when deciding whether to supplement horses


The simple answer to this question is it depends.

It depends upon several factors, for example:

How accurate your assessment is of what the horse’s supplement needs are.

  1. Refer to the previous section on “Should you give your horse supplements”.
  2. Noting that the horse and their environment is subject to change, so these needs may change over time for reasons such as season, age, level of work and presence / absence of diseases and disorders.

The quality of the horse supplement you select.

This involves selecting equine science supplements that:

  1. Is from horse feed manufacturers who are registered feed businesses. This means they are regulated and subject to inspection by their regulatory body. This also helps with peace of mind around feed hygiene and Hazard Analysis Critical Control (HACCP) practices.
  2. Has a composition (contains ingredients), as disclosed on the label, that are relevant to what you are looking for.
  3. The supplement ingredients are at levels that are meaningful to the horse’s diet ration.
  4. The ingredients in the supplement are bioavailable (the degree to which the substance is absorbed and made available) to the horse.
  5. The ingredients compliment any ratio requirements for the horse.
  6. From a secure and quality supply chain.
<img src="selectingaqualityhorsesupplement.jpg" alt="">
Infographic for selecting the best supplement for your horse

The scientific evidence and/or research behind the ingredients:

  1. Medicines must go through clinical trials and license approvals before being released to market. However, as we have already made a clear distinction above, under the section entitled “What is a horse supplement?”, a horse supplement is not an equine medicine, therefore these processes are not required for equine supplements.
  2. This means that equine supplements place greater reliance on the scientific knowledge underpinning the ingredients, as well as any clinical research carried out on those ingredients.
  3. Again, the body of equine research is continually growing but there may need to be a reliance on research carried out in respect to other mammalian species, should equine specific research be limited. This is standard practice. In such cases, comparisons are usually favoured depending upon the area of focus (e.g., across monogastric species, where stomach is in front of hindgut, when thinking about stomach digestion).
  4. When reviewing the research there are pros, cons and often remaining open questions so discernment in reaching an opinion and decision is required.

In summary, look to the scientific principles and available research behind the ingredients that help evidence why that is the best horse supplement for you, or not as the case may be.

Consideration is given to any known interactions or reactions the ingredients may have.

  1. For example, research on horses has demonstrated the benefit of herbs in several equine disorders, however, there are inherent risks to the use of some herbal supplements with respect to potential interactions with conventional drugs.
  2. Some herbs that humans can consume safely and are commonplace in human recipes may not be safe for horses.

The available budget you have.

  1. Perhaps you have narrowed it down to a few of the best equine supplements, but your financial budget may mean you need to rule one of those out due to cost.
  2. It can be useful to check the feed rate and see how many days you will get out of a particular equine supplement by dividing the price by the number of days to find out the cost per day. This lets you see that perhaps the initial outlay may be more than an alternative option but over time it will be cost effective for you.

Whether you follow the recommended feed rate or not.

  1. By following the feed rate for your horse, as provided on the horse supplement label, you are aligning with the horse feed manufacturers guidelines that, for a registered feed business, should have been thought through based on equine nutrition principles within safe levels.
  2. If you feed less or more then this may mean you experience more variable outcomes.

The consistency of use in line with the feeding guidelines.

If you feed the horse supplement in line with the feeding guidelines on the label in a consistent manner, then you are optimizing the supplement working for your horse. However, if the feeding guidelines state to use daily but you only use it every other day or weekly, then you are not setting things up for success.

<img src="stickynotes.jpg" alt="">
Sticky notes of equine supplement factors


To begin with, this question assumes you have selected the best horse supplement matched to the needs of your horse. Therefore having a chance of “working” in the first place, per the overview across the earlier sections.

It also depends upon your definition of “to work”. The horse cannot speak and give you verbal feedback on how they feel. So you will need to look for visual cues. Plus activity may be taking place within the deep structures of the horse that you cannot see. Therefore the reliance comes back to the underpinning scientific evidence and research behind the ingredients.

For example, an ingredient may be known to have cartilage supporting properties. But you will not physically be looking at their cartilage with the naked eye. However you may feel the difference in their movement after time. Or perhaps, the exterior of the horse shows new signs of thrive. That may be associated with use of that supplement for the horse. For example, hair shares protein with internal connective tissues, so the coat may also look better.

The answer is still dependent upon the supplement itself though. For example, what areas the supplement is expected to impact and how this is going to be measured. In summary, this duration will vary from supplement to supplement and horse to horse.



Choosing when to supplement horses, if at all, is personal to you and your horse. We encourage sharing of knowledge and adoption of a logical approach that reaches the right outcome. In addition, retaining flexibility to allow that decision to be adapted, as needs change over time is worthwhile.


Have you enjoyed this article? Then join us in Part 2 (coming soon) to look at:

  • What do different supplements do for horses?
  • How should you start a horse on supplements?
  • What to mix with horse supplements?
  • What horse supplements should not be mixed?
  • How many supplements is too much for a horse?
  • Why are supplements important for horses?


We are interested in what you think. Please do feel free to reach out to us with comments and questions.




Equine-X® is a registered feed business and the home of CONNEXION®. CONNEXION® is a feed material (aka: equine supplement / horse supplement) formulated to support equine connective tissues. Examples of equine connective tissues are tendons, ligaments, cartilage, bone, and fascia.


Interested in finding out more about the connective tissues in horses?

Then head over to our blog on this topic, available via this link: EQUINE CONNECTIVE TISSUE EXPLAINED (equine-x.com)

Interested in finding out more about the science behind CONNEXION®?

Then follow this link: Science – Equine-X

Leave a comment

  1. Supplement Horses - Considerations on how to do so (Part 2)
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