The basic principle, often forgotten, is that a supplement should complement the diet, not replace it. The starting point should always be an analysis of the whole ration: the quality and quantity of hay or pasture, the type of concentrate, the additions and the horse’s way of life. In many cases a well-chosen complete compound feed, together with good-quality forage, fully meets the animal’s needs, and extra products are not necessary.
The need for supplementation arises, among other times, when the horse’s feeding is based to a large extent on cereals such as oats, barley or high-energy feeds. Cereals are a rich source of energy, but poor in many minerals and vitamins. They also disturb the natural proportions of nutrients in the ration. What is more, they contain a lot of phosphorus and very little calcium and magnesium, which can upset the mineral balance. In such cases it is best to use a comprehensive vitamin and mineral supplement with well-balanced calcium, magnesium and trace elements (such as copper, zinc and manganese).
Supplementation is also justified in sport horses and those in hard work. In sweat the horse loses electrolytes such as sodium, potassium, chloride and magnesium, which it cannot always replace from feed and water alone. Shortfalls can show as faster fatigue, poorer recovery, muscle cramps or reduced fitness. In these cases electrolytes after training or competitions are sensible support, provided they are given consciously and in suitable amounts.
Another sign that a horse may need a supplement is visible evidence of shortfalls – weak, brittle hooves, a dull coat, a decline in condition, muscle stiffness or a drop in immunity. It is worth stressing, however, that the cause of the problem is often not supplementation itself, but mistakes in the basic ration. For example too little good-quality hay, an unsuitably chosen concentrate, or a lack of mineral balance.
A particular group that needs extra support is young horses, older horses, horses in convalescence, and in-foal and nursing mares. Young horses have an increased need for the minerals responsible for healthy bone development, older horses may absorb nutrients less well, and mares in milk lose huge amounts of minerals in the milk. In these situations, supplementation matched to that stage of the horse’s life is fully justified.
On the other hand, it is worth remembering that more does not mean better. Combining several supplements without a plan can lead to excesses, which can be just as harmful as shortfalls. That is why, before reaching for yet another product, it is worth pausing for a moment and asking whether we fully understand what the horse is already receiving in its feed.
To sum up, supplementation is justified when the ration does not meet the horse’s needs, and also in the case of intense work, particular stages of life, or the appearance of signs that may indicate shortfalls. If you are unsure, it is worth turning to an equine nutritionist or a veterinary surgeon and, if needed, running blood tests that will show the specific problems.