Peer-reviewed veterinary case report
Fertility of a stallion with low sperm motility and a high incidence of an unusual sperm tail defect.
- Journal:
- The Veterinary record
- Year:
- 1991
- Authors:
- Hellander, J C et al.
- Affiliation:
- Veterinary Department
- Species:
- horse
Plain-English summary
An eight-year-old standardbred stallion had serious issues with his sperm at the start of the breeding season, showing almost no movement and a high rate of defects in the sperm's tail and midsection. When his semen was collected daily, the movement of the sperm improved slightly, but the shape of the sperm did not get better. Despite these problems, the stallion was able to achieve a pregnancy rate of 24 percent per cycle and 44 percent over the entire breeding season with 32 mares. This suggests that even with the sperm defects, the stallion was still able to breed successfully, which is better than expected given his semen quality. Overall, the findings indicate that this specific sperm defect does not make the stallion infertile.
Abstract
At the beginning of the breeding season an eight-year-old standardbred stallion had semen with virtually zero sperm motility and an approximately 90 per cent incidence of midpiece and tail defects. The motility of the sperm improved to 7 per cent when semen was collected daily but its morphology did not improve. Electron microscopy revealed that the defects consisted mainly of a loss of microtubules in the axoneme and of disorganised midpieces. A pregnancy rate of 24 per cent per cycle and 44 per cent for the season was achieved in 32 mares after the insemination of whole ejaculates collected from the stallion frequently. The fertility was much higher than would have been expected from the characteristics of the semen. It is concluded that this sperm defect, reminiscent of the 'Dag defect' in bulls and the defect in T-locus mice, does not render the animal infertile.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/1858272/