Vitamin and Mineral Needs of Horses & Why Do The Levels in Supplements Vary So Much?
Copper, zinc, selenium, calcium, sodium, chloride, magnesium, vitamin E, Vitamin D, Vitamin B1, folic acid, biotin….. and these are just a few of the list of vitamins and minerals that can be fed to horses. Look at the label on a vitamin and mineral supplement and you may see 30 or more different ingredients listed. What’s more, if you compare the labels of two or more different products from different manufacturers you will almost certainly find that even for the same vitamin or mineral there are dramatic differences. What determines a horse or ponies vitamin and mineral requirements? There are a large number of different factors. For example, age, breed, soil type (on which forage was grown as some soils will be deficient for certain minerals and others may supply an excess), level of work, discipline (e.g. endurance versus racing versus eventing versus show jumping), level of competition (low to moderate to high) time of year, stage of growth (growing versus mature versus veteran), stallion, mare, mare in foal, gelding, underlying disease (e.g. respiratory disease, muscle disease, GI health), etc. In simple terms the requirements can probably best described by age and activity e.g. mature maintenance and or leisure (low-moderate activity), performance (mature moderate to high activity) and veteran (15 years or more and low to moderate activity).
So how should vitamin and mineral supplements for these three distinct groups be formulated? Well certainly it should not be random or by guesswork. There is a large volume of scientific literature concerning requirements and safe levels of different nutrients of the kind that are usually included in vitamin and mineral supplements. Much of this information is readily available to anyone in the form of published scientific papers; it’s simply a case of sitting down and being able to evaluate it and apply it. Much of the information has also been incorporated into consensus publications such as the NRC (National Research Council, USA) Nutrient Requirements of Horses 1 , the BASF and books such as Equine Applied and Clinical Nutrition3. With this in mind, why do different supplements vary so much? The first reason may be that many companies simply copy what is used by other companies. The second reason is that some ingredients are considerably more expensive than others and so some supplements may be formulated to meet a target cost rather than to meet requirements. Thirdly, some supplements may be formulated so that manufacturers can claim their supplement delivers the “most”, with the obvious risk of exceeding known safe levels. Finally, some supplements may have been formulated using inappropriate information, such as information from other species or outdated information. A good example of the latter is the continuing use of high levels of iron (chemical symbol Fe) in vitamin and mineral supplements when primary iron deficiency is extremely rare in horses and when horses have no mechanism for excreting excess iron leading to accumulation within tissues and oxidative stress.
So in summary, there is a wealth of knowledge which should be utilised when formulating vitamin and mineral supplements for the leisure, performance and veteran horse to ensure that safe and effective supplements are provided.
Dr David Marlin
1 NRC (2007) Nutrient requirements of horses. (6th Ed.) National Academy Press, Washington D.C.
2 Vitamins – One of the Most Important Discoveries of the Century (2000). BASF Documentation DC 0002. Animal Nutrition 6th Edition.
3 Equine Applied and Clinical Nutrition (2013) Geor, Harris and Coenen (editors), Saunders-Elsevier.