Modification of standard freezing media to limit capacitation and maximise motility of frozen-thawed equine spermatozoa.

The research article explores different techniques of preserving horse sperm, demonstrating that modification of the Kenney’s freezing medium method improves the motility and quality of the sperm after thawing.

Introduction and Methods

• The study was carried out to investigate changes that occur in horse sperm when it’s frozen, with a particular focus on the process of capacitation. Capacitation is a series of changes that sperm undergo before they can fertilize an egg.
• The researchers used three different types of preservation media, including Kenney’s Centrifugation Medium (KCM), modified Kenney’s Centrifugation Medium (MKCM), and Glucose-EDTA Centrifugation Medium (GECM).
• Semen was collected from three stallions, diluted in one of the three centrifugation media, centrifuged to remove supernatant, and extended in corresponding freezing media containing additional egg yolk, glycerol, lactose, and Equex paste.
• The samples were frozen in 5 mL straws, then assessed for sperm motility and membrane quality after thawing.

Results

• The results showed that sperm diluted with MKCM had higher percentages of normal F pattern (94.3%), than those in KCM (84.9%) and GECM (85.2%). Here, F pattern refers to sperm that have not undergone capacitation.
• On the other hand, more sperm exhibited capacitated B pattern in KCM (14.1%) and GECM (13.8%) than in MKCM (5.0%).
• After the freeze-and-thaw process, fewer sperm showed the acrosome-reacted (AR) pattern in modified Kenney’s Freezing Medium (MKFM) (45.6%), compared with Kenney’s Freezing Medium (KFM) (61.4%) and lactose-EDTA Freezing Medium (LEFM) (61.1%). Acrosome reaction is a critical step in capacitation, affecting fertilization success.
• However, there was a higher percentage of sperm showing the B pattern in MKFM (52.3%) compared with KFM (37.9%) and LEFM (38.6%).
• The type of freezing medium significantly affected the percentage of progressively motile sperm (those moving actively forward) after thawing. MKFM yielded the highest percentage of motile sperm (31.4%) compared to KFM (25.8%) and LEFM (23.3%).

Conclusion

• The researchers concluded that a modified version of Kenney’s freezing medium (MKFM) is the preferred medium for preserving horse sperm. It offers superior protection against motility changes and promises better membrane quality compared to the other freezing techniques researched.