Study: Stallion Semen Integrity Varies by Season

The month of the year appears to have a significant impact on several parameters of collected semen in stallions.

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Mares might not be the only ones with clear breeding seasons. Swiss researchers recently confirmed that stallion semen integrity also appears to be dependent on the season.

While seasonal variations of routine semen parameters are already well-documented, the amount of DNA fragmentation (DNA separating or breaking strands into pieces, which can cause sub- or infertility) also varies in stallions over the course of a year, with prominent differences between spring/summer and fall/winter, said Fredi Janett, DVM, and Dominik Burger. Janett works at the Clinic of Reproduction of the University of Zürich, while Burger is the head of equine reproduction research at the Swiss Institute of Equine Medicine of the University of Berne and Agroscope, in Avenches.

The month of the year appears to have a significant effect on several parameters of collected semen in breeding stallions, the pair relayed at the 10th annual Swiss Equine Research Day, held last year in Avenches.

In their study, they investigated ejaculates from 15 Swiss National Stud breeding stallions (the Franches-Montagnes breed) once a week for one year. They analyzed volume, sperm concentration, total sperm count, sperm motility, and susceptibility of the sperm DNA to denaturation (the destruction of the usual nature of a substance), which is associated with decreased fertility

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

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