The most important trace elements for horses are: iron, zinc, copper, manganese, iodine, selenium, cobalt, molybdenum, and sulfur. These minerals are needed in small amounts for the proper functioning of a horse.

Long-term Considerations

Trace elements are not always sufficiently present in roughage or grass. This usually doesn’t lead to an immediate problem, but in the long term, deficiencies can arise that affect your horse’s health. Trace elements must also be present in your horse's diet. For some of these minerals, it is important to avoid an excess.

Iron

Many minerals use the same absorption pathways in the horse’s body, which can interfere with each other. An excess of one mineral can cause a deficiency of another. Therefore, the correct ratios are very important. For example, iron absorption is limited if the feed contains too much cadmium, cobalt, copper, manganese, or zinc. Iron is needed to prevent anemia and ensure proper oxygen absorption and performance in sport horses. Horses on grass almost never have an iron deficiency.

Copper

Copper is important for the blood and several enzymes. It plays a role in the formation of connective tissue and the availability of iron. Copper helps with bone metabolism and is important during pregnancy, especially to give the unborn foal a good start. A copper deficiency can cause fragile bones and OCD in foals. An excess of copper is usually not problematic. Copper and zinc use the same absorption pathway, so too much copper can cause a zinc deficiency, and vice versa.

Zinc

Zinc is present in over a hundred enzymes. Among other things, the skin, liver, bones, and muscles contain zinc. A zinc deficiency reduces appetite, slows the growth of young horses, and can lead to skin problems. Zinc deficiencies are fortunately rare. Be careful of an excess, as it can lead to a copper deficiency.

Sulfur

Sulfur is essential for multiple bodily processes, especially those related to movement. Sulfur contributes to the formation of skin, hooves, ligaments, muscles, tendons, and joints. Additionally, sulfur is important for the immune system and to reduce allergies. Sulfur is needed in reasonable amounts daily. An excess of sulfur does not cause problems, as this mineral is excreted through urine and manure.

Iodine

Iodine is necessary for the formation of thyroid hormone, which regulates metabolism. This is very important, but be careful: an excess of iodine is toxic. The basic requirement for a 600 kg horse is 4.2 milligrams, and 40 milligrams can already be toxic. The iodine content in feed products and balancers varies widely. For example, some balancers and feeds contain no iodine at all. Products like seaweed, however, can contain high levels of iodine. An iodine deficiency in a pregnant mare can cause thyroid problems, OCD, or even stillbirths in foals. Fertility problems can also occur. So, if you plan to breed, make sure to check how much iodine your horse is getting in total.

Selenium

Selenium, together with vitamin E, is important for muscle metabolism. It also protects cells as an antioxidant and is important for growth. A selenium deficiency can result in decreased immunity, growth issues, stiffness, or lethargy. Selenium deficiencies in grass/forage are common on sandy soils. On clay soils, this is less frequent. Be cautious: an excess of selenium is very toxic! An excess can occur at around eight times the daily requirement. Hair loss can be a symptom of too much selenium.

Manganese, Cobalt, and Molybdenum

Manganese is essential for carbohydrate and fat metabolism. It is also very important for the production of chondroitin, which plays a key role in cartilage formation. Cobalt is a building block of vitamin B12. This is important for enzymes, blood, skin, and growth. Molybdenum supports the hormone balance. There are no known issues with excess amounts of these three trace elements.

Balancer and Mineral Buffet

To ensure that your horse receives enough minerals and trace elements, you can give a balancer. Make sure you feed enough and check the packaging to see if, for example, iodine and selenium are included in the balancer. You don’t want to miss these, but you also shouldn’t feed too much. Be mindful of other supplements, such as seaweed and vitamin E, where iodine and/or selenium may be present. It is also wise to occasionally switch the balancer so your horse gets everything it needs. Minerals from the Barents Sea can also be a source of various mini-trace elements that your horse might not otherwise get. You can give these liquid minerals as part of a mineral buffet, where your horse can choose what it needs.