Zinc is one of the most important trace elements in equine nutrition, together with iron, copper, and selenium. Zinc has numerous roles in the body. It is involved in the horse’s energy metabolism and hormone function. It supports vitamin A function and improves wound healing. Zinc is especially recommended for horses with skin issues and for horses suffering from poor-quality coat, mane and tail hair, or weak hooves. Zinc can also help strengthen a horse’s skin after sweet itch and rain rot. A horse’s daily zinc requirement is 500–600 mg/day depending on workload, and a foal’s requirement is 300 mg/day.
CdG Zinc - Zinc for horses 500 g, 29,90 €
Zinc regulates, among other things, the insulin sensitivity of the horse’s cells and therefore the body’s sugar metabolism. Zinc deficiency causes lower insulin concentrations after eating and weakens the body’s ability to utilise carbohydrates. This, in turn, may impair recovery from training and the development of muscles. In competition horses, it is worth noting that zinc (about 20–21 mg/l) and also a small amount of copper are lost in sweat. This should be taken into account especially in summer when horses sweat more.
Various feeding studies show that under normal feeding, horses can easily develop deficiencies—particularly in zinc and copper, and also in manganese. This is because the concentrations of these minerals in the horse’s main feeds, hay and oats, are often fairly low. These important trace elements are linked, among other things, to iron absorption, so deficiency in them can be a reason for low iron values in blood tests, for example. Other deficiency symptoms include a poor coat, slow-healing wounds, itchy and flaky skin, immune system disturbances (including allergies and other inflammatory conditions), licking, nervousness, and general fatigue. Poor hoof quality can also indicate zinc deficiency. Zinc requirements increase during pregnancy and lactation as well as during heavy work. According to some research, eating soil, sand, or manure, as well as wood chewing, may be linked to iron or copper deficiency and an incorrect copper–zinc ratio in the diet (Aytekin et al. 2011).
The important zinc–copper ratio and musculature
Adequate zinc and copper intake is especially important for foals’ normal growth and skeletal formation. In addition, it is important that the ratio is correct. Too much zinc reduces copper absorption. The copper:zinc ratio should be approximately 1:4. The amount of zinc that impairs copper absorption depends on existing copper stores in the body. Together, zinc and copper also help prevent physitis. Physitis appears as swelling of joints and issues in joint cartilage.
Most zinc (50–60%) is located in muscles. When a horse begins systematic training, it is also necessary to think more carefully about feeding. Excess protein intake can impair zinc absorption and increase zinc excretion from the body. At the same time, adequate protein is needed for muscle development. Excessive calcium and copper intake can also reduce zinc absorption. Zinc may support healthy blood sugar levels by improving insulin sensitivity and increasing antioxidant status, which may be lacking in horses with EMS.
8 reasons to feed zinc to your horse:
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Antioxidant protection: Zinc supports antioxidant defence. Antioxidant enzymes convert harmful oxidants or free radical particles into neutral, harmless compounds. Cells naturally produce free radicals as nutrients are broken down into energy, but over time these can damage cells. By improving antioxidant status, zinc helps protect against premature ageing and supports healthy tissues and cells. Horses in heavy work produce more harmful oxidants and may benefit from extra antioxidant support. In one study (2), heavily trained Thoroughbreds were given an antioxidant supplement containing zinc and copper. The antioxidant capacity of horses receiving the supplement improved during the training period (3). Older horses typically have lower antioxidant enzyme levels, and therefore they may benefit from additional zinc.
- Hoof health: A proper balance between zinc and copper supports keratin synthesis. Keratin is the main hoof protein and creates a strong hoof structure. Horses with an optimal zinc–copper ratio have a lower risk of white line disease and a lower risk of hoof wall separation (4).
- Immune function: Zinc helps immune cells respond to infections. When an infection is detected, blood zinc levels drop as immune cells and the liver take up this mineral. A temporary drop in blood zinc during infection has been shown in horses suffering from fever and cellulitis (5). With zinc, immune cells can signal to other cells to coordinate immune response. It is assumed that adding zinc to a diet that is otherwise fairly low in zinc can improve immune response.
- Skin health: Horses with zinc deficiency may show various skin abnormalities, such as flaking or slow-healing wounds. This may be due to weakened immune function. Horses deficient in zinc may be more prone to rain rot, which results from bacterial overgrowth on the skin in wet conditions. A well-functioning immune system is more effective at fighting pathogens. Adequate zinc in the diet can support healthy skin and improve coat quality and shine.
- Insulin levels and insulin sensitivity: Zinc also contributes to maintaining insulin sensitivity. This refers to how well cells respond to insulin to move glucose out of the bloodstream (7). In humans, zinc supplementation has been shown to improve insulin sensitivity in obese individuals. In other animals and in humans, low blood zinc is associated with insulin resistance and diabetes (6). This mineral affects insulin secretion from pancreatic cells and can help ensure that the correct amount of insulin is released to control blood sugar. Zinc’s effect on insulin sensitivity has not been studied directly in horses. However, zinc is crucial for antioxidant status, and oxidative stress is a key factor in insulin resistance. Ensuring adequate zinc intake may reduce the risk of metabolic disorders. It is particularly important that horses with metabolic syndrome or Cushing’s/PPID receive enough zinc to support proper insulin function.
- Joint health: Zinc is required for the production of collagen protein, which makes up much of the tendons and ligaments of joints. It is also required for cartilage production. In one study (8), the diet of horses in moderate work was supplemented with a mixture of copper, zinc, cobalt, and manganese either in organic or inorganic form. After 12 weeks, horses fed organic minerals had clearly higher marker levels of collagen synthesis. These horses may tolerate harder training and exertion and may be less prone to joint wear. This study also shows that organic trace minerals may support collagen production in joints better than inorganic minerals.
- Coat quality: Zinc contributes to keratin production, the most abundant protein in hair. Keratin is also responsible for hair structure. Horses supplemented with organic forms of zinc and copper had stronger and more elastic hair fibres than horses given inorganic forms (9). Horses with a dull, faded, and fluffy coat may have zinc deficiency and may not produce enough melanin. The deficiency is easiest to observe in red and black horses, which require more melanin for dark coat colour. These changes in coat colour and quality may also indicate copper deficiency.
- Appetite: Zinc deficiency can cause poor appetite, weight loss, and poor growth. Foals with severe zinc deficiency have been shown to have low appetite and slow growth (10). This is linked to chemical changes in the hypothalamus, which regulates food intake. Ensuring adequate zinc intake may support normal appetite and healthy weight gain in horses.
Factors leading to low zinc levels
There are several factors that can affect zinc absorption and utilisation in the body. The best-described are interactions with other minerals that affect absorption from the gastrointestinal tract. Zinc, copper, and iron are known to compete for the same absorption pathways in the intestines. If your horse eats feed that is high in iron, this can impair the absorption of zinc and copper from the diet. Elevated iron levels in the body can also affect how tissues use zinc. High calcium levels in feed have also been shown to reduce zinc bioavailability.
Zinc overdose is very rare. The best sources of zinc are mineral feeds and supplements. Flaxseed, pumpkin seeds, and brewer’s yeast are fairly good sources of zinc. Bran also contains a relatively good amount of zinc.
Lähteet:
- Eamens, GJ et al. Skeletal abnormalities in young horses associated with zinc toxicity and hypocuprosis. Aus Vet J. 1984.
- Marreiro, DN et al. Zinc and Oxidative Stress: Current Mechanisms. Antioxidants. 2017.
- de Moffarts, B et al. Effect of oral antioxidant supplementation on blood antioxidant status in trained thoroughbred horses. The Vet J. 2005.
- Higami, A. Occurence of white line disease in performance horses fed on low-zinc and low-copper diets. J Equine Sci. 1999.
- Murase, H et al. Serum Zinc Levels and Their Relationship with Diseases in Racehorses. Int Med. 2012.
- Chausmer, Arthur B. Zinc, Insulin and Diabetes. J Am Col Nutr. 1998.
- Cruz, KJC et al. The Effect of Zinc Supplementation on Insulin Resistance in Obese Subjects: a Systematic Review. Biol Trace Elem Res. 2016.
- Dickson, Emily C. Effect of Complexed Trace Mineral Supplementation on Joint Health in Young, Exercising Horses. Texas A&M Univ Lib. 2018.
- Malgorzata, K et al. Effect of diet on mechanical properties of horse’s hair. Acta Bioeng Biomech. 2009.
- Baltaci, KA and Mogulkoc, R. Leptin and zinc relation: In regulation of food intake and immunity. Ind J Endo Met. 2012.
- Mills, CF. Dietary interactions involving the trace elements. Annu Rev Nutr. 1985.
- Madden, V. Zinc Toxicosis in Horses. US EPA. 2005.
