Although horses only need relatively small amounts of vitamins, a lack of these tiny amounts can be detrimental to your racehorse’s health and performance.

 

Vitamins comprise one of the six general groups of nutrients–the other groups are water, carbohydrates, proteins, fats, and minerals. Vitamins are organic (carbon-containing) compounds that are needed in relatively small amounts by the body to support normal metabolism in the body. Vitamins cannot be synthesized within the body in sufficient amounts; therefore, they must be supplied in the horse’s diet.

 

When vitamins are not provided in optimum amounts at the tissue level, deficiency symptoms can occur for each vitamin. However, sufficient amounts might be produced in some species or stages of development, but not others. For example, guinea pigs, can’t producevitamin C from glucose. In contrast, most horses produce enough vitamin C, but young racehorses, old and sick horses might benefit from supplementation.

 

Vitamins are classified according to their solubility, which determines the site in the body where they function. Body tissues are primarily composed of watery or fatty substance, Vitamins that function in the watery areas are called water-soluble vitaminsand include vitamin C and the B-complex vitamins. Vitamins that function in the fatty tissues are called fat-soluble, and include vitamins A, D, E, and K.

Solubility influences a vitamin’s mode of action, storage capability, and toxicity. The B vitamins, except B12, are not stored in the body. They enter the body, make their way inside a cell and outside a cell in to the extracellular fluids. They are excreted via the urine. Most water-soluble vitamins function as co-enzymes in energy, protein and amino acid metabolism. Some are co-substrates in enzymatic reactions (such as vitamin C in oxidation/reduction reactions), or are structural components and regulatory agents, such as choline and inositol in phospholipids.

 

Fat-soluble vitamins A and D are stored in the liver and can be viewed as hormones, since they are produced in one location and function in another location. They are not as easily absorbed as water-soluble vitamins and can be toxic if over-consumed.

 

Vitamin E and the vitamin A precursor (building block) beta-carotene are stored in adipose (fat) tissue and are not considered toxic. Vitamin K is a co-enzyme and has both water-soluble and fat-soluble varieties; it is necessary for the proper formation of blood clots.

Vitamin A aids in vision, bone remodelling, and the maintenance of healthy skin cells. Signs of vitamin A deficiency can include signs such as, night blindness, excessive lacrimation or tears, hyperkeratinisation of the cornea and skin, anorexia and reproductive failure.

Prolonged feeding of large amounts of vitamin A can cause toxicity signs, including bone fragility, rough hair coat, poor muscle tone, and ataxia.

Vitamin D3 (cholecalciferol) is formed in the skin of animals from irradiation of 7-dehydrocholesterol by sunlight. Two vitamin D3 metabolites (products of vitamin D3 metabolism) act on the intestines, bones, and kidneys to regulate calcium balance and promote the synthesis of calcium-binding proteins.

There are no documented cases of vitamin D deficiency in horses unless they are kept inside away from all sunlight.

 

Vitamin D toxicity, on the other hand, involves calcification of soft tissues, blood vessels, heart, andor kidneys due to bone resorption abnormalities. Supplementation of vitamin D, if needed, is recommended at 10% of the amount of supplemental vitamin A.

Vitamin E is a broad-spectrum lipid (fat) antioxidant that functions in cell membranes and improves the immune response in horses. It is also an effective antioxidant in both feeds and body tissues. Acetate forms of vitamin E are stable until digested in the intestine, and they are the most common forms in feeds.

 

Deficiency of vitamin E can result in several diseases in horses, including equine degenerative myeloencephalopathy (EDM) and equine motor neuron disease (EMND).

 

 Vitamin E is recommended for horses prone to tying-up (exertional rhabdomyolysis) and to support optimum recovery times post training and racing. Horses being fed rations with additional added oil will benefit from supplemental vitamin E because of its antioxidant activity. As a rule of thumb 100 iu of extra vitamin E are required for every 100ml of supplemental oil.

 

Recent studies show that the natural-source form of vitamin E is about three to four times more effective in horses than the form in synthetic sources.

Vitamin K is required for blood clotting, but no requirement has been established for horses. However, it has been shown that 20 mg/day can be safely fed to performance horses. The use of vitamin K to prevent or lessen exercise-induced pulmonary haemorrhage (EIPH, or bleeding in racehorses) is currently being studied.

 

Under normal circumstances, horses do not need dietary vitamin C, since they are able to manufacture it from glucose. Under conditions such as hot weather, stress and high-level performance,horses might benefit from vitamin C supplementation.

 

B vitamins are necessary for the metabolism of carbohydrates, proteins and fats. The bran and germ from cereal grains (such as wheat and rice) and brewer’s yeast are excellent sources of B vitamins. B vitamins (except B12) are found in good-quality forages and are synthesized by bacteria in the equine hindgut.

 

Dietary B vitamin supplementation might be beneficial in hard-working horses as well as horses fed high-cereal rations, such as traditional high cereal racing feeds. All of these horses might have an altered population of bacteria in the hindgut due to low fibre intakes.

 

Horses have some level of need for each vitamin, which depends on their size, age, reproductive status, gender, temperament, and work load. The exact amounts needed are unknown, as there has not been as much vitamin research done in horses as in other species. However, some progress has been made in discovering minimum amounts required to prevent deficiency, maximum amounts that result in toxicity, and optimum ranges for performance.

 

Today, virtually all commercial animal feeds are fortified with vitamins. Pay close attention to the manufacturers recommended minimum feeding amounts to ensure a balanced ration.

Before you jump to adding supplements to your current ration remember that twice as much does not equate to twice the performance but more twice the cost and an increased risk of creating an imbalanced ration or toxicity that may compromise performance and recovery rates.

 

A young racehorse needs optimum levels of minerals to keep building healthy new bone and muscle while he’s exercising to the limit. Calcium and phosphorus are the two macrominerals that have the biggest impact on his growth. If both are not present in sufficient quantity, and in the correct proportions (at least as much calcium as phosphorus), your young racehorse won’t be able to construct sound, dense and resilient legs.

 

Forages and hay, as a whole, tend to be high in calcium and low in phosphorus, while most cereal grains (oats, maize and barley) are the reverse. Because racehorses tend to eat such cereal-dense diets they frequently run the risk of taking in more phosphorus than calcium. Adding limestone to the ration, is one of the simplest solutions; it can be added to the feed at a level of 60g a day if necessary. However, a well formulated commercial ration will already provide the optimum ratio of calcium and phosphorous.

 

To determine how much calcium and phosphorus really are being delivered in the diet a hay analysis can be performed and this is a service that we provide when working together with our clients. Interpreting the analysis together with the other feeds and supplements in the ration we can determine the optimum calcium and phosphorous ratio to ensure an optimum balance within the total finished ration.

 

Two other minerals that play a significant role in the growth and development of healthy bones, cartilage, and connective tissue are zinc and copper. Like calcium and phosphorus, these two minerals have a synergistic effect in the body.

 

Iron is an essential component of haemoglobin, the molecule in the blood that helps carry oxygen to the cells. It’s common, at the racetrack, to supplement iron in the name of “blood-building” for optimum performance. However, true iron deficits are unlikely unless the horse is experiencing chronic blood loss.

 

Most forages and alternative fibre sources such as beet pulp contain far more iron than the average horse could use, so real iron deficiencies are rare.

 

Copper deficiency will cause the same type of anaemia commonly attributed to iron deficits. Excessive iron supplementation interferes with copper utilization and can make things worse.

 

One essential supplementation to the ration of a racehorse is salt. It is easy to underestimate how much sodium and chloride a horse can lose when he is exerting himself and sweating. I recommend providing ad-lib access to a salt block in addition to adding additional salt to the ration. Salt is one of the only nutrients that horses will actively go to seek out and consume to their requirement.

 

So, optimum levels of vitamins and minerals are essential to support optimum performance, recovery and health. Its easy to blame poor or reduced performance or a poor blood test on a vitamin or mineral deficiency and ‘top up’ with that magic potion or blood tonic. However, before doing that consider a full ration evaluation that takes into account your management and training strategies to see if performance can be optimized with the correct feed to balance your forage source. This can usually be done free of charge and with no obligation. You may be pleasantly surprised!

 

By Lizzie Drury MSc Rnutr of Saracen Horse Feed proudly distributed in the Middle East by Eurovets Veterinary Suppliers