May 2014 - Do horses need extra supplements in their rations?
The article is written by Dr. Dag Austbø at the Norwegian University of Life Sciences institution. Dr. Dag Austbø and Dr. Knut Hove are two of the key people behind the development of PC-Horse. Their scientific work and international networks contribute to the continued development of PC-Horse and to secure that our calculations are based on established scientific data.
There are many types of supplements for horses on the market. Supplements are also often included in rations without a real need for them being established or their effects having been documented.
Vitamin and mineral supplements
The most common type of supplements are vitamin and mineral supplements. These products often contain vitamins A, D, E plus several B vitamins and vitamin C. In addition, they contain a wide spectrum of macro and micro minerals. The purpose of these products is to ensure that the ration contains enough of these vitamin and mineral nutrients.
Where the horse's ration consists mainly of roughage or roughage and grains (oats or barley) a vitamin/mineral supplement will generally need to be included. Most supplements have a balanced nutrient content that is effective as long as manufacturer's recommendations for use are followed.
Concentrate mixtures for horses contain vitamins and minerals. By using the amounts recommended by the manufacturer (usually about 0.5 kg per 100 kg bodyweight/day) the products should help to deliver a balanced amount of the nutrients needed in your horse's ration. Further supplements should not be needed if the roughage is of normal quality. Horses in light exercise or that have become too fat need to be fed less concentrate mixture than the manufacturer recommends. For these horses it is appropriate to provide vitamin/mineral supplements, but the amounts must be adjusted according to how much concentrate mix they receive. They should therefore not be given the full amount of vitamin/mineral supplements in addition to the full amount of concentrate mixture.
Some supplements contain only a few vitamins or minerals. Typical of these are products that contain mainly vitamin E and selenium (Se). When using these supplements we should remember that all concentrate mixtures for horses already contain both vitamin E and selenium. Selenium is also a highly toxic mineral that can easily be overdosed.
Electrolytes are important in the maintenance of fluid balance and normal functioning of the body. The major electrolytes are sodium (Na), chloride (Cl) and potassium (K +). Calcium (Ca + +) and magnesium (Mg + +) are also essential electrolytes but required in in small amounts. Sodium and chloride are found in common salt (NaCl). Potassium is mainly found in roughage. Typically, the content of potassium in grass, hay or silage is around 15-20 grams per kg dry matter. If the ration contains enough roughage, then it also contains about 3-5 times more potassium than the daily requirement. The need for sodium is difficult to cover through the feed alone. We must therefore make sure that the horse is getting enough salt. Several experiments have shown that horses do not regulate their own salt uptake satisfactorily from salt blocks. We should therefore give them salt directly with the feed to be sure salt needs have been met. This is especially important for horses in training who sweat a lot and thus lose a great amount of salt through sweat. After hard training or competition, a horse loses more than 100 grams of salt through sweat.
Most electrolyte supplements contain salt and sugar plus potassium, calcium, magnesium and some trace elements. It is important to be aware that the most common electrolyte supplements do not cover the horse's need for sodium. We must always ensure that the horse gets enough salt.
Through the intensive exercise involved in endurance races or competitions over several days it may become necessary to supplement with an electrolyte product as there may be a need for additional supplementary potassium, calcium and magnesium.
Some supplements consist mainly of herbs. These are given in small amounts and contribute little to the horse's nutritional status. It is generally claimed that they have health-promoting effects but there remains insufficient evidence for this . Some herbs contain alkaloids and other plant substances (phytochemicals) where the effect on horses is unknown. This type of product must be used with caution. For competition horses it is particularly important to be certain that these kind of supplements do not contain substances that may be prohibited by doping regulations. There are many examples of "safe and natural" supplements that have resulted in positive doping tests in both humans and horses.
Garlic is one of the most popular supplements for both humans and horses, and is known to have numerous health effects. However, garlic contains allicin that can cause anemia (Heinz body anemia). It is uncertain what a safe daily amount of garlic may be for horses, but experiments have shown that a daily intake of more than 0.2 grams of freeze-dried garlic per kg bodyweight led to changes in red blood cells and anemia in horses (Pearson et al . , 2005) .
Garlic Is also given to horses to reduce insect pest in the summer months. There is no evidence that this has any effect.
Probiotics , prebiotics and yeast
Probiotics are products with live bacteria that can improve digestion and create a healthy intestinal flora. Common types of bacteria are lactic acid bacteria.
Prebiotics are different types of indigestible carbohydrates (fibre) that stimulate the growth of beneficial intestinal bacteria. Common prebiotics are fructo-oligosaccharides (FOS), inulin and resistant starch.
The effect of pro- and prebiotics on horses is insufficiently documented and the results of experiments vary. However, this type of supplement involves little risk of adverse side effects and is therefore used on many horses to help ensure good gut health and to prevent diarrhea.
There are many types of yeast products on the market. They may contain dried yeast, yeast culture or yeast extract. Dried yeast and yeast culture contain live active yeast to stimulate fibre digestion, while yeast extract is an extract of yeast cells that are inactive and is supposed to stimulate the intestinal flora and improve performance. The most common yeast culture in such products is Saccharomyces cerevisiae (ordinary baking yeast).
The effects of using yeast supplements is not well documented, but studies have shown improved digestibility of some feed components and increased growth in young horses. Use of yeast supplements for horses is generally considered harmless and dried yeast is also added to some types of concentrate mixtures.
Vitamin and mineral supplements will help balance your horse's ration for these nutrients. PC-Horse will help you decide whether your horse needs additional vitamins or minerals. Electrolytes are important, especially for horses in training. Most important of all is to secure the intake of common salt. Electrolyte products can be important for horses in strenuous competitions, such as endurance rides and competitions over several days. For pro- and prebiotica, herbs and yeasts, no requirements can be given. The individual horse owner must evaluate the use and safety of such products. Always be sure that the products you include in the ration are safe according to health and doping regulations.
What does this mean in practice?
Daily intake of roughage varies based on feed quality, production classes, individual appetite and each individual's place in the herd hierarchy. This means that we must observe horses in a herd closely and make corrections to the feed offered each individual at night-time or early morning to avoid some individuals growing too fat or too thin.
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