Just like broodmares, stallions can sometimes use some extra support. Especially if they are also used in the sport or do a lot of breeding. Of course, not everyone has a KWPN breeding stallion in their stable, but there are quite a few people in the Netherlands and Belgium who breed with Shetland ponies or their own crosses, for instance. What should you pay attention to in the diet for optimal fertility of a stud? Although stallions do not carry the foal and therefore do not need to get the building blocks to build a foal's skeleton, for example, like broodmares do, they still have special nutritional needs. These are mainly to do with fertility.

Optimum fertility stud

You want a breeding stallion to be as fertile as possible. This is to avoid disappointments and a lot of effort, energy and travel costs for both stallion and mare owners. In some breeds, such as shetlanders and Friesians, the sperm quality of stallions is not always optimal. The sperm are not always sufficient, well structured or mobile enough. Especially if the semen is still diluted or frozen for travel, it is important that the quality is very good. So the stud must be optimally fertile. In humans, fertility has been much studied. Up to 80% of fertility problems in men are related to so-called 'oxidative stress' and reduced antioxidant activity in the sperm. To remedy that, you need so-called antioxidants in the diet. These are vitamins such as vitamin C and vitamin E.

Vitamin E for fertility

One of the most important vitamins for fertility is vitamin E. This applies to both stallions and mares. Research shows that giving extra vitamin E in the feed, can result in higher sperm production and a better structure of those sperm cells. The sperm cells are also (much) more motile, increasing the chances of fertilisation. Vitamin E is found in fresh grass. If your horse is in a nice green pasture all day, the amount of vitamin E that comes in with grazing is usually more than sufficient. When grass is dried to make roughage, most of the vitamin E is lost. Hay still contains very little of this essential nutrient. This means that in winter you often have to feed supplementary feed. A supplement is also a good idea if your horse spends a lot of time in the paddock, or on a bare pasture. The body does build up a supply of vitamin E, but it eventually runs out. This is often at the end of winter, just when you want your breeding animal's fertility to peak. Supplementing vitamin E in winter is therefore a good idea for studs and brood mares. Horses that run in sport have a higher consumption of vitamin E because this substance is also very important for muscle building. Studs and broodmares in sport therefore have an even higher requirement.

Immune system at the right level

To get a horse as fertile and healthy as possible for the breeding season, it is important that its resistance and immune system are up to scratch. Vitamin E is important for this too. But other substances such as plant cannabinoids from cloves and vitamin C also play a role in good immune function. It is also important that your horse (mare or stallion) is neither too fat nor too lean. A healthy weight is important for low inflammation levels and optimal fertility.

Which vitamin E should you feed?

The best absorbable form of vitamin E for horses is so-called 'natural vitamin E'. That sounds a bit crazy, because vitamin E is a natural substance. But the molecule can be produced in several ways, with the structure sometimes being just a tiny bit different. Many cheap supplements contain so-called 'synthetic' vitamin E, which is often very difficult to absorb, especially for horses. In humans this is less of a problem, as our bodies use this substance much better than a horse's body. The best absorbable form of vitamin E is RRR-α-tocopherol. This is found in wheat germ oil, for example. The so-called synthetic vitamin E is the isomer dl-α-tocopherol acetate. This is often found in cheaper vitamin E supplements and is poorly absorbed by horses. It seems cheaper, but ends up being expensive. Besides vitamin E, other antioxidants are also important for better fertility. A good supplement is, for example, vitamin C - which is also found in grass - or the strong antioxidants from grape germ oil, for example.

Dose high? No selenium!

Finally, be careful with vitamin E supplements that also contain selenium. If you want to give a horse extra vitamin E because they train and cover a lot or are carrying a foal, a combined supplement is unsuitable. This is because selenium is toxic in high doses. While you may want to feed quite a lot of vitamin E. So choose a vitamin E that contains the natural isomer and is selenium-free for your broodmares and stallions.   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/