Effect of semen collection practices on sperm characteristics before and after storage and on fertility of stallions.

The study investigates the impact of various semen collection practices and intervals on the quality, quantity and fertility of stallion semen, both fresh and post-storage. It concludes that the efficiency of semen collection techniques can greatly affect the sperm’s integrity and the resulting fertility rates in mares.

Experiment 1: Fractionated vs Non-fractionated Sperm Collection

• The research began by comparing the sperm quality extracted through fractionated (separated into parts) and non-fractionated techniques. It was observed that the overall sperm quality was not affected by the type of collection and was similar for both methods.
• However, centrifugation (spinning at high speed to separate particles) of sperm-rich fractions led to improved motility (movement ability) and membrane integrity after thawing compared to non-centrifuged fractions. These results indicate that centrifugation of sperm fractions before freezing could potentially enhance sperm quality.

Experiment 2: Effect of Collection Frequency on Sperm Quality

• The next experiment examined the impact of how frequently the semen is collected from the stallions. They compared sperm collected once daily and twice every 48 hours, 1 hour apart.
• The first ejaculate of double collections displayed higher sperm concentrations and percentages of motile sperm, suggesting that more frequent collection might be beneficial.
• However, semen collected only once daily showed fewer live sperm after freezing and thawing than the first ejaculate after twice collections, indicating that collection frequency might impact the sperm’s survival rate after freezing.

Experiment 3: Correlation Between Collection Practices and Sperm Count

• In this stage of research, the scientists studied the relationship between the time taken to ejaculate, the number of mounts, and the sperm count. An increase in sperm volume and total count was observed when the time to ejaculation and the number of mounts increased.
• However, they also noted a decrease in sperm concentration and motility with increased time to ejaculation and the number of mounts, raising potential concerns about the quality of sperm over quantity.

Experiment 4: Impact of Collection Practices on Pregnancy Rates in Mares

• In the final experiment, the researchers retrospectively studied the correlation between semen collection frequency, the number of mounts per ejaculation, and the pregnancy rates in mares.
• While semen volume increased with increasing mounts, the sperm concentration and percentage of motile sperm decreased after 24-hour cool-storage. This brings attention to the possible deterioration of sperm quality with increased collection attempts.
• The study also found a statistically significant relationship between the frequency and interval of semen collection and the foal rates in mares. Mares inseminated with semen from frequently collected stallions exhibited substantially higher foaling rates than those that received sperm from stallions with less frequent collection schedules.