Sperm population structure in high and low field fertility rams

Area of Science:

• Reproductive biology
• Animal science
• Spermatozoa analysis

Background:

• Field fertility in rams is crucial for efficient breeding programs.
• Understanding sperm characteristics can help predict fertility outcomes.
• Sperm morphometry and kinematics are key parameters in assessing sperm quality.

Purpose of the Study:

• To determine if ram field fertility differences correlate with sperm morphometric and kinematic subpopulations.
• To investigate the association between sperm morphometric and kinematic subpopulations.
• To identify reliable indicators of ram fertility.

Main Methods:

• Collected ejaculates from high and low fertility rams over six weeks.
• Utilized computer-assisted sperm analysis (CASA) for motility.
• Employed computer-assisted sperm morphometry-fluorescence for nuclear morphometry.
• Applied clustering procedures and logistic regression for data analysis.

Main Results:

• Identified three distinct kinematic and three morphometric sperm subpopulations.
• Observed significant differences in subpopulation distribution between high and low fertility rams.
• Found higher percentages of fast, linear-moving sperm and large, long-nuclei sperm in high fertility rams.
• Total progressive sperm motility and proportion of large, long spermatozoa were significant fertility predictors.

Conclusions:

• High and low fertility rams exhibit clear differences in sperm morphometric and kinematic subpopulations.
• Total progressive sperm motility and the proportion of spermatozoa with large, long heads are consistent indicators of ram fertility.