Dr Vicki Glasgow, Equine specialist with Harbro

All living things require minerals and vitamins to thrive and survive but what do they do and how can you ensure that your horse or pony is receiving all that it requires?


Minerals are required for a variety of functional needs; including skeletal integrity and cellular processes for all functions in the body. They are split in to two main groups; macro-minerals and trace minerals.

Macro-minerals are required in relatively large amounts and include calcium, phosphorous, magnesium and the electrolytes, sodium, potassium and chloride. The requirements of these change depending on age and stage and work load.

The balance of these minerals to each other is just as important as the absolute levels. In particular, the balance of calcium to phosphorous is crucial and particularly so in growing and/or breeding animals.

Trace minerals, as the name suggests, are required in very small amounts but this doesn’t make them any less important. These include copper, selenium, zinc, cobalt, manganese, iron and iodine etc.

These also need to be in the correct balance as well as being present at a minimum recommended level. Excesses of one can affect uptake of another.


Vitamins are also required for bodily processes and as in the case of Vitamin E, act as powerful anti-oxidants mopping up harmful free radicles.

They are also split in to two main groups – fat soluble and water soluble. Fat soluble includes vitamins A, D, E and K, and water soluble include the B complex vitamins and vitamin C.

When a horse is healthy and its hindgut bugs are also healthy, it can manufacture its own B-vitamins and vitamin C. Sometimes gut health is compromised, however and sometimes requirements can outstrip what is provided by these bugs.

This is especially true in horses that are in higher levels of work and travelling lots. In theory, horses that receive plenty of sun-cured fresh hay and outdoor exposure to sunshine should have plenty of vitamin D.

Unfortunately, the reality in Scotland is that we don’t get so much sunshine and especially in the winter months this will still need supplemented.

Getting the right balance?

It is possible to have an analysis done of your forage and pull together a balanced diet that way.

The truth is, however, that one bale of hay, or haylage can be very different from another from the same field let alone hay from different sources and/or different cuts. It is, perhaps surprisingly, actually oftentimes better to use average results for hay mineral analysis (thousands of samples from across Scotland) which is what we nutritionists use to ensure your feeds and mineral supplements provide a balanced diet for your horse if fed correctly.

As a general rule, if your horse falls in to one of the below categories then supplementation with a good quality vitamin and mineral supplement is recommended:

1. Only gets hay and grass (forage only diet)

2. Is fed on forage and straights (eg oats, grass nuts, beet pulp)

3. Is fed on forage plus hard feed at less than the recommended level

Good doers and others that are on restricted rations are at the highest risk of deficiencies.

Recommended feeding levels

This is normally on the feed bag and tells you how much to feed for your particular horse’s weight and activity level.

If you feed less than this level, then your horse’s diet will be short of vitamins, minerals and trace elements. If you want to continue to use the same feed, then my advice is to use a broad spectrum vitamin and mineral supplement, or balancer to make up for the shortfall.

Be careful not to over supplement, however, as too much can often be as damaging as too little. Most nutrients and minerals have interactions with several other minerals and changing the amount of one can result in another becoming deficient.

If you have cut back the nuts, or mix to 20% of the recommended level, then only use 80% of the product that you have chosen to top up with or vice-versa.

It is a case of using simple proportions to not only prevent over supplementation but also to save throwing money down the drain, or more literally in to the muck heap! If in doubt speak to a nutritionist and make sure you have labelling information and feeding recommendations to hand.

Forage only diet

If your horse is on a forage only diet, or is a good doer and therefore should be on a forage only diet, my advice would be to use a vitamin and mineral supplement (check out Harbro One Scoop), alongside a low calorie chaff, to supply the whole of your horse’s vitamin and mineral requirements.

This means that you are not supplying any extra calories and will reduce the likelihood of weight gain. Forage and grazing are usually the culprits for weight gain and the way that these are fed should also be assessed and restricted accordingly.

Feeding straights can actually make a horse’s diet more unbalanced than just feeding forage. Horse’s fed on straights should almost certainly be supplemented with a vitamin and mineral supplement or a balancer (check out balancers from Gain, Spillers and Topspec to name but a few) where quality protein is supplied as well as vitamins and minerals.