Deciphering sperm chromatin properties to predict stallion sperm fertility

Area of Science:

• Animal Science
• Reproductive Biology
• Veterinary Medicine

Background:

• Previous research focused on sperm DNA fragmentation index and stallion fertility.
• Other crucial aspects of sperm chromatin structure and packaging in relation to fertility remained unexplored.

Purpose of the Study:

• To investigate the relationship between fertility and various sperm chromatin parameters in stallions.
• To explore DNA fragmentation index, protamine deficiency, total thiols, free thiols, and disulfide bonds in stallion spermatozoa.

Main Methods:

• Collected ejaculates from 12 stallions (n=36).
• Utilized flow cytometry with acridine orange (Sperm Chromatin Structure Assay for %DFI), chromomycin A3 (protamine deficiency), and monobromobimane (thiols and disulfide bonds).
• Analyzed data using mixed linear models and correlated findings with per-season pregnancy rates.

Main Results:

• Negative correlations observed between pregnancy rate and %DFI (r=-0.35) and free thiols (r=-0.60).
• Positive correlations found between total thiols and disulfide bonds (r=0.95), and protamine and disulfide bonds (r=0.41).
• Chromatin integrity, protamine deficiency, and packaging were all associated with fertility.

Conclusions:

• Sperm chromatin integrity, protamine deficiency, and packaging are significantly associated with stallion fertility.
• A combination of these factors can serve as a reliable biomarker for assessing ejaculate fertility in stallions.