Correlation between bull fertility and sperm cell velocity parameters generated by computer-assisted semen analysis

Area of Science:

• Reproductive Biology
• Animal Science
• Veterinary Medicine

Background:

• Sperm motility is crucial for assessing fertilizing ability and semen quality.
• Traditional semen analysis relies on subjective motility assessments.
• Computer-Assisted Semen Analysis (CASA) offers objective and repeatable evaluation of sperm kinematics.

Purpose of the Study:

• To evaluate kinematic parameters of frozen-thawed bull semen using CASA.
• To correlate specific sperm velocity parameters with in vivo fertility (pregnancy rate).
• To identify the most predictive motility characteristic for bull fertility.

Main Methods:

• Semen from 10 bulls was collected, frozen, and thawed.
• Sperm kinematic parameters, including curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP), were measured using CASA.
• Fertility was assessed by comparing CASA data to pregnancy rates in nearly 9,000 artificially inseminated females.

Main Results:

• Individual velocity parameters showed varying correlations with fertility.
• Average Path Velocity (VAP) demonstrated a significant correlation with the achieved pregnancy rate.
• The study focused on individual velocity parameters rather than overall progressive motility.

Conclusions:

• Average Path Velocity (VAP) is the most clinically relevant semen motility characteristic for predicting bull fertility.
• CASA-based VAP measurement provides a valuable tool for improving artificial insemination success rates.
• Objective kinematic analysis enhances the accuracy of semen quality assessment.