The truth about minerals, vitamins and pasture-only diets: Hygain Nutrition series

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The natural feeding habit of the horse is to eat small amounts of roughages often. A forage-only diet is deficient in several critical vitamins and minerals, and therefore horses must be supplemented. Minerals and vitamins are vital to performance, growth, immune function and reproduction. To ensure your horse is in optimal health, it is important to provide a well-balanced mineral supplement.

When feeding horses, we often concentrate on the major components of the diet. Does the horse have enough pasture, hay, chaff or even hard feed? We can sometimes recall the amount of protein, but most other nutrients seem unimportant. However, it is the intake of these other nutrients, the small things, which keep horses healthy. 

During the spring when there is an abundance of grass, it’s easy to overlook mineral and vitamin supplementation when horses are gaining weight. Just because a horse is in optimal body condition (or even overweight), it does not mean they are getting the nutrients they need; it simply means they are being provided sufficient calories.


Minerals are inorganic elements needed by all animals to remain healthy and productive. Minerals can be divided into two broad classifications; macro-minerals and micro-minerals, based on the amount required in the diet. Macro-minerals are required in large amounts in the diet. They include calcium, phosphorus, magnesium, potassium, sodium, chlorine, and sulphur. These minerals are vital to the development of the skeleton, muscle contraction, acid-base balance, activity of the nervous system, hormones hoof and hair growth.

The other classification of minerals is micro (or trace) minerals. These minerals are required in small amounts in the horse’s diet, and include copper, iodine, iron, manganese, cobalt, selenium and zinc.  These minerals function in most of the chemical reactions in the body, helping to metabolise nutrients, maintain connective tissue and joint tissue, aid in oxygen transport to muscle, and perform as antioxidants.


Vitamins are equally important. Vitamins are classified as either fat-soluble or water-soluble, based on how they’re stored within the body. The major fat-soluble vitamins include vitamins A, D, and E. These vitamins are important for vision, calcium absorption and regulation, and as a primary antioxidant protecting cells and muscle function. Fat-soluble vitamins are stored within the fat deposits of the body and can accumulate, giving the potential of toxicity if overfed.

Water-soluble vitamins, often referred to as B-vitamins, include thiamin, riboflavin, niacin, biotin, and folic acid.  These vitamins function in nearly every chemical reaction within the body; therefore, they are critical in metabolism, growth, and energy generation. The B-vitamins are manufactured by healthy bacteria within the horse’s digestive system and specific requirements have only been established for thiamin and riboflavin.

Many people provide horses with a trace mineral salt block with the assumption that this will provide everything their horse needs. Unfortunately, not all mineral needs may be satisfied. The typical trace mineralised salt block provides only a fraction of a horse’s needs, and does not provide major minerals (except sodium and chloride) and vitamins. Most trace mineralised salt blocks contain 96% or more salt, and a small amount of minerals.

Detecting deficiencies

Many horse owners are oblivious to the vitamin and mineral content of the diet, as a mild deficiency is difficult to see. While a deficiency in calories can easily be seen as weight loss, and a deficiency in protein can be seen as a rough coat or poor growth, a deficiency of minerals or vitamins is much more difficult to notice until the condition is severe. Less obvious signs of mineral and vitamin deficiency are cracked and brittle hooves; the result of zinc deficiency and a crooked- legged foal could be the result of a broodmare diet deficient in trace minerals. 

Feeding a horse a correctly balanced diet is not hard if we remember that the small things (vitamins and minerals) are important.      

How can we ensure our horses’ diets are properly fortified with essential minerals and vitamins? 

The easiest approach is to feed a premixed feed or supplement that is properly fortified with these nutrients. We must ensure that we are feeding the product according to label directions. If we are only feeding half of the recommended feeding level, our horse will not be receiving the proper amount of nutrients. 

What do we do about overweight horses who don’t require the calories that are in a premixed feed? 

Feeds with concentrated protein, vitamin and mineral supplements are designed to be fed at low rates without the need to add grain. HYGAIN® BALANCED® provides essential minerals and vitamins without the added calories.

HYGAIN® BALANCED® should be fed at a rate of 0.1% of the horse’s body weight (500g for a 500kg horse).

Get a free personalised diat analysis for your horse: follow the five easy-step HYGAIN Nutrikey form at the link below and have a nutrition consultant assess your horse’s diet.