Unfortunately there are some horses, who despite receiving the correct nutrition, encounter fertility problems and, whilst additional nutritional support cannot claim to solve all these problems, it can certainly help in some cases.

Key Nutrients

Omega 3 Fatty Acids

Research has shown that Omega 3 fatty acids are essential for reproduction, and a deficiency results in infertility. Horses are incapable of manufacturing these fatty acids, so they must be available in the diet but a high grain diet is especially likely to be deficient and supplementation may prove beneficial. With regards to stallion fertility, research in other species has shown that supplementing with dietary fatty acids can increase the number of healthy sperm and decrease those with abnormalities. These fatty acids are directly incorporated into cells where they help to create stronger membranes, which can better withstand the aggressive processes of freezing and thawing, making supplementation particularly useful for stallions participating in AI programmes.

Research has also shown that the long chain polyunsaturated fatty acid DHA (Omega 3) is found in large concentrations in brain and retinal tissue, indicating its important role in development of the foetus. Studies have found that supplementation of the female’s diet with Omega 3 fatty acids results in offspring that perform better on visual, problem solving and intelligence tests, when compared to offspring in an unsupplemented group, and that the benefits of these fatty acids are also passed through the milk to their young. Omega 3 fatty acids are metabolised to anti-inflammatory compounds in the body, which is thought to help reduce the inflammatory response that often occurs in the mare’s reproductive tract following natural covering or AI, thus increasing the chance of conception.


Although Omega 3 fatty acids have many beneficial effects, they do not work in isolation and interactions with other nutrients must be considered. The antioxidants, vitamins E and C and selenium, function synergistically and help to increase fertilisation rates and the numbers of active sperm. Selenium is also vital for sperm formation, and a deficiency has been shown to result in abnormalities and decreased fertility. Other nutrients, including beta-carotene (vitamin A) and zinc, also have proven benefits for increasing fertility.


Zinc is essential for reproduction and hormonal regulation in both sexes and contributes towards maintaining an optimal sperm count, playing a major role in motility and the stabilisation of membranes. Beta-carotene increases fertility and libido and is particularly beneficial to mares as it stimulates ovarian activity, increases pregnancy rates and reduces the incidence of cyclic disorders.

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