Nutrients, Minerals, and Vitamins

Minerals, trace elements, vitamins, amino acids, and yeasts in horse nutrition: what their roles are and when supplementation in horse feed is advisable.

On the back of a dietary supplement, you’ll find columns of numbers: zinc 20,000 mg, selenium 45 mg, vitamin E 6,000 mg, along with abbreviations like 3b607 or 3a700. It’s understandable that most people just skim over these labels.

But there’s more to it than just the numbers. Each of these nutrients has a very specific role in a horse’s body, and understanding them allows you to assess rations and supplements much more effectively. That’s exactly what this article is about: explaining from the ground up what macronutrients, trace elements, vitamins, amino acids, and yeasts actually do.

Why hay and concentrated feed often don’t provide everything

A horse fed exclusively on forage generally meets its energy and fiber needs well. The situation is different when it comes to micronutrients, for several reasons:

The mineral and trace element content in hay depends on the soil in which it was grown. In Germany, there are entire regions with selenium-deficient soils, and the situation is similar for zinc and copper. Then there’s the harvest time: hay cut late in the season has more crude fiber but lower nutrient density. And storage adds to the cost ‒ vitamins, in particular, are sensitive to light and time. Vitamin E levels are significantly reduced after prolonged storage.

Then there’s the horse’s actual nutritional needs. A sport horse, a pregnant mare, a growing foal, or a horse that has just undergone stressful transport has different requirements than a leisure horse that goes out for two rides a week.

That’s why, when it comes to supplemental feed, it’s not about “more is better,” but about filling in the gaps.

Macronutrients: the building blocks in grams

Horses need macronutrients in relatively large quantities, specified in grams per day.

Calcium and phosphorus together form the mineral substance of bones and teeth. What matters here is not only the quantity but also the ratio between the two. An excess of phosphorus can impair calcium absorption. Grains provide a lot of phosphorus, while hay ‒ and alfalfa in particular ‒ provide a lot of calcium, which is why the ratio shifts depending on the diet.

Magnesium plays a role in muscle function and in the transmission of nerve impulses. For horses that appear nervous or tense, it is often the first supplement administered.

Sodium and chloride ‒ collectively known as table salt ‒ are lost through sweat. Horse sweat is saltier than human sweat, and a salt lick only meets the horse’s needs if the horse actually uses it.

Potassium is abundant in roughage. A deficiency rarely occurs here, except in cases of heavy sweating.

Trace Elements: Small Amounts, Big Impact

Trace elements are measured in milligrams, and sometimes in micrograms. The amounts are tiny, but their functions are not.

Zinc is involved in over a hundred enzymes and plays a role in skin, coat, hoof horn, and immune function. It is one of the trace elements most commonly lacking in German forage.

Copper contributes to the formation of connective tissue and pigments. Zinc and copper compete for absorption, which is why their ratio in a mineral supplement is not left to chance but is the result of careful formulation.

Manganese is involved in cartilage and bone metabolism.

Selenium is part of the cell’s antioxidant defense system and works in conjunction with vitamin E. Selenium has a relatively narrow range between the required amount and an excess, making it a prime example of why maximum levels are listed on labels.

Iodine is needed for thyroid hormones, iron for oxygen transport in the blood, and cobalt as a component of vitamin B12.

Organically or inorganically bound?

One point that’s easily overlooked on labels but is practically relevant: trace elements can exist in different chemical forms. Zinc sulfate is inorganic, while a glycine-zinc chelate is organically bound. Organically bound forms and selenium yeast are considered to have better bioavailability, meaning the horse can actually utilize more of them. Even when the label lists the same amount, the actual amount absorbed can vary.

Vitamins: what horses can and cannot produce on their own

Vitamins are divided into two groups, and this classification explains a great deal about how they should be fed.

Fat-soluble vitamins include vitamins A, D, E, and K. They require fat for absorption, can be stored in the body, and are therefore the group for which excess intake is actually a concern. Vitamin A is produced from beta-carotene, which is abundant in fresh grass but scarcely present in stored hay. Horses produce vitamin D through sunlight exposure on their skin, which is naturally limited during the German winter. Vitamin E protects cells and is particularly important for muscle metabolism.

Water-soluble are the B vitamins and vitamin C. They are hardly stored at all; the horse excretes any excess. Here’s a special point to note: A healthy horse’s gut produces B vitamins through the microorganisms in the large intestine itself, and unlike humans, horses can also produce vitamin C on their own. However, this is only true as long as the gut flora is functioning properly. During periods of high exertion, after stress, or in cases of digestive upset, supplementation may be advisable.

Biotin deserves its own mention because it is by far the best-known vitamin in equine nutrition. It plays a role in the formation of keratin, the building block of hoof horn, skin, and hair. What is often underestimated here is that hoof horn grows slowly; results are only visible after several months.

Amino Acids: Why Crude Protein Alone Doesn’t Tell the Whole Story

„Crude protein 12 percent“ on a feed analysis is a quantity specification, not a quality specification. What matters is which amino acids are present in that protein.

The body uses amino acids to build new protein, such as for muscles, tendons, or enzymes. If even a single one is missing, the synthesis stalls ‒ even if all the others are present in excess. This is why it’s referred to as the limiting amino acid. In horses, this is usually lysine, followed by methionine and threonine.

This explains an observation many owners make: A horse is fed a high-protein diet yet still fails to build muscle. Often, it’s not the quantity that’s lacking, but the right amino acid profile.

Yeast: Not a Nutrient, but Support for the Gut Flora

Yeast is a special case in this list because it does not serve as a nutrient itself, but rather influences conditions in the gut. And the gut is the horse’s actual center of digestion: In the large intestine, microorganisms break down the crude fiber from the hay, which the horse could not utilize without them.

There are two distinct forms. Live yeast, usually Saccharomyces cerevisiae, actively enters the gut and can stabilize the environment there for the fiber-degrading bacteria. On the label, it is listed as a zootechnical additive with a CFU value, i.e., colony-forming units. Inactivated yeast and yeast cell walls, on the other hand, provide nutrients and structures that serve as a substrate. Selenium yeast is an example of the second group; here, the yeast acts as a carrier for an organically bound trace element.

The timing is interesting: Yeasts typically come into play when there is a change in the gut flora. Examples of such moments include a change in feed, turning out to pasture, transport, competitions, or deworming.

Electrolytes: what sweat carries away

Electrolytes are not a separate class of nutrients, but rather the minerals present in the body as charged particles: primarily sodium, chloride, potassium, and magnesium. They regulate fluid balance and muscle function.

When a horse sweats, it loses precisely these substances - and in significant quantities. A horse working intensely can lose several liters of sweat. Plain water replaces the fluid, but not the salts. That’s why a combination of water and electrolytes makes more sense after exercise than water alone.

More is not better: why labels list limits

With micronutrients, there is no linear increase. Too little is a problem, too much is as well, and for some nutrients, there is little leeway between the two.

That’s why you’ll find statements on dietary supplements such as „may only be fed up to a maximum of 1 percent of the daily ration” and the note to take into account the nutrient intake from other feeds. This is more important than it sounds: If you combine a mineral supplement, a muesli with additives, and a trace element supplement, you’re adding up levels that might seem unremarkable on their own.

Interactions are just as relevant. Zinc and copper compete for the same absorption pathways; calcium affects the utilization of other minerals; and selenium works in tandem with vitamin E. A formula is therefore more than just the sum of its individual components.

Practical advice: Supplement specifically rather than broadly, and consult your veterinarian if you suspect a deficiency. A blood test and an assessment of your pet’s diet can determine exactly which deficiency exists.

Reading the Label: A Brief Guide

The categories on the packaging are legally defined and provide information about usage and dosage:

• Feed material consists of a single component, such as flaxseed oil or psyllium husks.
• Complementary feed specifically supplements a diet but is not suitable as a complete feed.
• Mineral feeding stuff is a complementary feed with high mineral content intended for basic nutritional needs.
• Dietary complementary feed is intended for a specific nutritional purpose, which is stated on the packaging.

And the three sections of the label: Composition lists the raw materials in descending order of quantity. Analytical constituents specify measured levels such as crude protein or crude fiber. Additives per kilogram or per liter lists the added vitamins, trace elements, amino acids, and yeasts along with their EU authorization numbers ‒ that is, abbreviations such as 3a700 for vitamin E or 3b607 for zinc as glycine-zinc chelate.

In a nutshell

Minerals build and regulate; trace elements activate enzymes; vitamins control metabolic processes; amino acids provide the building blocks for protein; yeast maintains the balance of the intestinal flora; and electrolytes regulate water balance. No nutrient acts alone, and the amount alone is only half the story. Form, ratio, and requirements are also key factors.

All JuloVet products are developed in collaboration with veterinarians and manufactured in Germany, tested according to GMP+ and QS standards. They are available exclusively through veterinary practices, for one simple reason: The best place to determine which supplement is right for which horse is where the horse’s diet, housing conditions, and blood profile are known. Ask your veterinarian about JuloVet products.

FAQ

What nutrients does a horse need daily?

In addition to energy, crude fiber, and water, a horse needs macronutrients such as calcium, phosphorus, magnesium, sodium, and chloride; trace elements such as zinc, copper, manganese, selenium, and iodine; fat-soluble vitamins such as A, D, and E; and sufficient protein with an appropriate amino acid profile. Requirements depend on weight, age, performance level, and condition.

What is the difference between macronutrients and trace elements?

The difference lies in the required amount. Macronutrients are measured in grams per day, while trace elements are measured in milligrams or micrograms. Both are equally important; trace elements primarily function as components of enzymes.

What does „organically bound zinc“ or „organically bound selenium“ mean?

„Organically bound“ means that the trace element is bound to an organic carrier, such as an amino acid in the form of a glycine chelate or yeast in the case of selenium yeast. These forms are considered to be more bioavailable, meaning the horse can utilize a larger proportion of them than with inorganic compounds such as zinc sulfate.

What is the benefit of yeast in horse feed?

Live yeast cultures support the gut flora and can stabilize digestion, especially during periods of transition and stress such as a change in diet, transport, competition, or deworming. Inactivated yeast also serves as a carrier for organically bound trace elements.

Which amino acid is most important for horses?

In practice, lysine is considered the primary limiting amino acid, followed by methionine and threonine. Limiting” means that if it is lacking, protein synthesis stalls, even if there is enough protein overall in the diet.

Does my horse need additional mineral supplements when grazing in the pasture during the summer?

Fresh grass provides significantly more beta-carotene and vitamins than stored hay. When it comes to minerals and trace elements, however, the amount depends on the soil composition, and the need for sodium and chloride actually increases in the summer due to sweating. A basic supplement is therefore usually advisable.

Is it possible to overdose a horse on minerals?

Yes. For fat-soluble vitamins and some trace elements ‒ especially selenium ‒ the margin between the required amount and an excess is very narrow. That’s why complementary feed lists maximum daily allowances and includes a warning to account for nutrient intake from other feed sources. Only combine multiple supplements after consulting with a professional.

Gastro Vital Aktiv supports gut flora and helps stabilize digestion. It can positively influence acid regulation in the gastrointestinal tract and help counteract the effects of stressful situations such as competitions, stable changes, deworming, or diet changes. Available as Gastro Vital Aktiv powder, Gastro Vital Aktiv Liquid, and Gastro Vital Aktiv Booster for direct administration. Developed in collaboration with veterinarians; ADMR-compliant.