Stallion Supplements: Do They Work?

Among the various supplements given to stallions in hopes of improving semen quality, some are more effective than others, and evidence is conflicting as to whether still others have any effect at all. One supplement ingredient that seems to make a difference is DHA, an omega-3 fatty acid found in fish oil. When stallions supplemented with DHA were compared with a control group that did not receive the supplement, semen from both groups showed good sperm motility after 24 hours of cooling, but the sperm from treated horses swam straighter and faster. After 48 hours, changes were more obvious, with sperm from treated horses showing better total motility, progressive motility, and rapid motility. Stallions whose cooled semen usually doesn’t cool well were significantly improved by the supplementation.

Lipids, a group of substances including fatty acids, are highly concentrated in sperm and sperm membranes, and the different amounts and concentrations account for the differences in how well semen from a particular species will react to cooling and freezing. The supplement used in the study was designed for boars, whose semen has some of the same characteristics as stallion semen, namely a similar distribution of polyunsaturated fatty acids (PUFAs) and a low tolerance to cold shock. Some other animals like bulls and roosters produce sperm with a different distribution of PUFAs that makes their sperm membranes tolerant of cold shock, so that they generally freeze well.

Studies in humans and other animal species have shown that supplementation with vitamins C and E and a combination of L-carnitine and L-acetyl-carnitine have improved sperm output, concentration, and motility. It is not known whether these supplements would have any effect, positive or negative, on sperm quality in stallions.