How many vitamins and minerals does my horse need?

Every horse needs vitamins and minerals for all its daily life functions. But how many exactly? And which vitamins and minerals are especially important? We list them for you, including some important facts about your horse's nutritional needs.

4 February '25 - 4 min reading time

There are of course many minerals, vitamins and also amino acids that your horse needs. Many of these substances are present to a greater or lesser extent in roughage, such as hay or grass. For many horses it is wise to also give a balancer or to supplement the minerals and vitamins in another way.

Important vitamins and minerals for your horse

The table below shows your horse's daily requirements for the most important vitamins, minerals and essential amino acids.

Mineral/ Vitamin	Basic requirement per kg body weight	Basic needs of a horse 600 kg
Calcium^	0.052gr	31 gr (44^)
Phosphorus^	0.037gr	22 gr (22^)
Magnesium^	0.015 gr	9 gr (22^)
Sodium	0.026 gr	16 gr
Potassium	0.065gr	39 gr
Silicon	0.002 mg	120 mg
Copper	0.2 mg	120 mg
Iron	0.8 mg	480 mg
Zinc	0.8 mg	480 mg
Manganese	0.8 mg	480mg
Selenium**	0.002 mg	1.2 mg
Iodine**	0.007 mg	4.2 mg
Cobalt	0.001 mg	0.6 mg
Chrome	Not known	Not known
Sulfur	0.03 gr	18 gr
Vitamin A	30 IU	18,000 IU
Vitamin D3	6.6 IU	3,960 IU
Vitamin E	1 mg	600 mg
Vitamin B1	0.06 mg	36 mg
Vitamin B2	0.04 mg	24 mg
Lysine ^^^	0.054 gr	32 mg
Micro/trace elements^^^^	0.02 ml	12 ml

Legend:

gr = gram

mg = milligram

µg = microgram

ml = milliliter

IE = International Units (also called IU)

Comments on table:

^ = Calcium, phosphorus and magnesium follow the same absorption route in the body and can get in each other's way. If you feed too much calcium, the absorption of magnesium can be lower, for example. You should therefore not only look at the minimum amount of each of these minerals that your horse needs, but also at the ratio between the three. The ideal calcium/phosphorus/magnesium ratio for an adult horse is 2:1:1. This will often mean that with a sufficient amount of phosphorus and calcium, you will have to feed more than the minimum requirement for magnesium, see the numbers in brackets in the table. Magnesium is often the bottleneck, especially because it is found in small quantities in Dutch hay. A solution for this is to feed a form of magnesium that is not absorbed via the same route as calcium and phosphorus. This is magnesium chelate, which is seen by the body as an amino acid and is therefore more easily absorbed, for example magnesium oxide.

^^ = avoid overdosing on selenium and iodine: these elements can be toxic from about eight times the basic requirement.

^^^ = For the amino acid Lysine to work properly, it is important that the horse also receives sufficient vitamin B6. However, no basic requirement standard is known for this.

^^^^ = You do not necessarily have to supplement trace elements every day, for example by providing a mineral buffet that the horse can choose from.

Basic need or more?

The basic requirement shown in the table applies to an adult horse that is not working and not pregnant. Horses that are in training have a higher requirement for vitamins and minerals. This is often around 10 to 15% more, but in the case of vitamin E, for example, this is 1.5 to 2 times as much. Pregnant mares also have a higher requirement, especially in the last months of pregnancy. For complete tables, please visit Voervergelijk.

Is everything being recorded?

If you offer the right amounts of vitamins and minerals to your horse, through hay, feed and possibly a supplement, then it is logical to think that your horse can meet its needs. In many cases this will be the case. However, it is good to realize that there are factors that can negatively influence the absorption of vitamins and minerals. We already mentioned above the competition between the minerals calcium, phosphorus and magnesium, which are absorbed via the same route and therefore must be given in the right proportion. But vitamin A and vitamin E can also compete with each other, and this also applies to the absorption of zinc and copper. Too much of one can cause a deficiency of the other.

Other things to note:

Bacteria, fungi and yeasts in the feed (due to poor storage) cause lower intake

Reduced absorption due to worm damage in the intestines

Too few healthy fats in the diet, which means that certain vitamins are not properly absorbed (for example vitamin E)

Reduced bile function in the intestines can also disrupt vitamin absorption

Stress and illness have a negative effect on the absorption of minerals and vitamins

Different horse breeds differ in metabolism and absorption

Custom made

For potassium and zinc, it has already been shown that there is a difference between, for example, English Thoroughbreds and Arabians in how much they absorb in their blood, with the same amount in the feed. Unfortunately, this type of information is not yet available for all horse breeds. Because, for example, the worm history of a horse is also important for the actual absorption, it remains wise to always keep a close eye on your horse. Does your horse show signs that indicate a possible deficiency or excess? Then adjust your ration. A blood test can also provide more insight into some of the vitamins and minerals. Not for all of them, by the way, because the body has a 'reservoir' of certain substances, for example in the liver or in the bones. If there is a deficiency, the reservoir is first used, but the blood picture remains the same. You often only notice a deficiency late, because problems arise. Your vet can tell you for which substances it may be useful to 'draw a blood sample' in your horse.