Vitamin E plays an important role in improving fertility in mares. In humans, this has been known for some time. But this vitamin also has a positive effect in horses. Vitamin E is often used together with other antioxidants. It increases the fertility of mares and stallions and improves the resistance of breeding mares and their newborn foals. The efficacy of vitamin E in humans with fertility problems has been well studied. A number of scientific studies have also been conducted on horses.

Vitamin E deficiency

Vitamin E is an incredibly important vitamin. Not only for fertility, but also for your horse's muscles and nervous system. It is a powerful antioxidant. As horses do not produce vitamin E themselves, it has to come from their diet. Grass contains a lot of easily absorbable vitamin E and horses that spend all day at pasture will therefore get enough vitamin E. The situation is different for horses that mainly eat hay or haylage. Especially sport horses and horses used for breeding have a higher need for vitamin E. They can become deficient if they are not on grass and also do not get a supplement.

More fertile mare and stallion and more resistance

In stallions, sperm quality and sperm motility increase when given extra vitamin E. This increases the chances of successful fertilisation. In mares, supplementing vitamin E not only improves fertility, it is also good for transferring immune substances to the foal in the last month before delivery. When the mare gets enough vitamin E, it also ensures a higher quality of colostrum (first milk) that her foal gets to drink. This means that the foal is better protected against diseases and bacteria in the first period of its life.

Grass?

Most foals are born between February and June. By then, by no means all broodmares are already (fully) on pasture. Researchers therefore recommend giving mares extra vitamin E one month before and one month after foaling. A good vitamin E status ensures greater transmission of immune substances. That transfer occurs before birth via the placenta and then via the mare's colostrum. A mare that gets enough vitamin E can therefore give her foal a better and healthier start! Foals and young horses with severe vitamin E deficiency can develop the muscle disease NMD.

Fertilisation

Vitamin E is also very important for successful conception. Studies in humans found that in 30-80% of cases of fertility problems in men, oxidative stress and reduced antioxidant activity were found in the sperm. This would indicate a lack of antioxidants such as vitamin E, which can be supplemented through diet. Extra vitamin E resulted in more sperm, which were also less likely to be damaged. Taking vitamin E is also recommended for women to improve fertility. Many women also take vitamin E to reduce menstrual complaints and PMS.

'Natural' vitamin E

In horses, supplementing vitamin E comes very accurately. This is because by no means all types of vitamin E are absorbed well. The best absorbable form of vitamin E is the isomer RRR-α-tocopherol. This is found, for example, in wheat germ oil. This is popularly called natural vitamin E, but since you can also make RRR-α-tocopherol in a factory, 'naturally occurring vitamin E' is a better name. What you shouldn't have for your horse is 'synthetic vitamin E', by which dl-α-tocopherol acetate is meant. This is often found in cheaper vitamin E supplements. This isomer is very poorly absorbed by horses and is therefore often 'a waste of money'.

Conclusion: Choose strong antioxidants for better fertility

For improving fertility, the antioxidant action of vitamin E is very important. To supplement deficiencies, it is best to choose natural vitamin E, or RRR-α-tocopherol. Studies on fertility in humans and horses often used a combination of antioxidants, including vitamin C. One of the strongest antioxidants on the market for horses is grape extract. A combination of this with natural vitamin E, possibly supplemented with vitamin C, is therefore recommended. Especially if your breeding animals cannot eat any or little grass. Vitamin E is also an important supplement for the immune system of mare and foal.   Sources: Deichsel K, Palm F, Koblischke P, Budik S, Aurich C. Effect of a dietary antioxidant supplementation on semen quality in pony stallions. Theriogenology. 2008 May;69(8):940-5. doi: 10.1016/j.theriogenology.2008.01.007. Epub 2008 Mar 20. PMID: 18358523. https://pubmed.ncbi.nlm.nih.gov/18358523/ Contri A, De Amicis I, Molinari A, Faustini M, Gramenzi A, Robbe D, Carluccio A. Effect of dietary antioxidant supplementation on fresh semen quality in stallion. Theriogenology. 2011 Apr 15;75(7):1319-26. doi: 10.1016/j.theriogenology.2010.12.003. Epub 2011 Feb 4. PMID: 21295825. https://pubmed.ncbi.nlm.nih.gov/21295825/ Ahmadi S, Bashiri R, Ghadiri-Anari A, Nadjarzadeh A. Antioxidant supplements and semen parameters: An evidence based review. Int J Reprod Biomed. 2016 Dec;14(12):729-736. PMID: 28066832; PMCID: PMC5203687. https://pubmed.ncbi.nlm.nih.gov/28066832/ Mohd Mutalip SS, Ab-Rahim S, Rajikin MH. Vitamin E as an Antioxidant in Female Reproductive Health. Antioxidants (Basel). 2018;7(2):22. Published 2018 Jan 26. doi:10.3390/antiox7020022 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5836012/ Kentucky Performance Horses. Vitamin E: An Essential Nutrient for Horses. Review. 2018. https://kppusa.com/2018/03/02/vitamin-e-essential-nutrient-horses/