Effect of milk fractions on survival of equine spermatozoa.

This research article investigates the impact of different components of milk on the survival of horse semen during storage, showing that some elements offer protection while others negatively affect survival rates.

Introduction

• The study focuses on examining how various fractions of milk impact the motility or movement of stallion spermatozoa or sperm cells, which is crucial for successful conception.
• Milk-based semen diluents are utilized for storing horse semen due to their known protective properties; however, the specific constituents of milk that either support or harm the spermatozoa are not yet fully understood.

Methodology

• The researchers tested several fractions such as native phosphocaseinate (NPPC), beta-casein, whey protein concentrate (WPC), alpha-lactalbumin, beta-lactoglobulin, microfiltrate, and ultrafiltrate.
• The absorption and benefits of these fractions were compared to standard reference diluents such as INRA 82, commercial skim milk, and Hank’s salts solution supplemented with Hepes, glucose, lactose (HGLL) supplemented with Bovine Serum Albumin (BSA).
• Spermatozoa survival was recorded after 48 and 96 hours of storage at low temperatures (4 or 15 degrees C).

Findings

• The research found that certain milk fractions (ultrafiltrate, microfiltrate, and alpha-lactalbumin fraction) reduced the survival rates of sperm cells.
• In contrast, other components (beta-lactoglobulin (BL) and native phosphocaseinate) acted as protective agents for the sperm of the stallion.
• More specifically, native phosphocaseinate (NPPC) at milk concentration was discovered to provide better protection than the standard reference diluents.
• The beta-lactoglobulin at an optimal concentration offered better protection than Bovine Serum Albumin (BSA).
• The research noted that the protection given to the stallion spermatozoa by native phosphocaseinate did not amplify when combined with beta-lactoglobulin, indicating that the two components may share a similar protective mechanism.

Conclusions

• The study found no difference in motility of semen diluted in HGLL augmented with NPPC (HGLL-NPPC), or in INRA 82 and stored for 24 hours at temperatures of 15 degrees C or 4 degrees C, respectively.
• However, the fertility rate of semen stored in HGLL-NPPC (60%) was significantly higher than that stored in INRA 82 (36%).
• These findings suggest a more nuanced understanding of how different milk fractions can optimize the protection of horse semen during storage, with potential applications in equine reproduction and breeding programs.