Abstract
Background:
Seminal plasma and sperm play vital roles in fertility because they contain various proteins that influence sperm quality and function.

Aim:
This study aimed to compare the protein profiles of seminal plasma and sperm in Bali and Wagyu cattle and evaluate their correlation with fresh semen quality.

Methods:
The study was conducted at the Singosari National Artificial Insemination Center using 3 Bali and 3 Wagyu superior bulls aged 5–12 years. Sperm motility parameters were analyzed using computer-assisted sperm analysis (IVOS-Hamilton). Sperm were extracted using the PRO-PREPTM Protein Extraction Solution. Sperm and seminal plasma protein concentrations were measured using the BCA protein assay, and 1D SDS-PAGE was used to analyze protein profiles. The gels were stained with Coomassie Brilliant Blue to visualize protein bands.

Results:
Comparative analysis of semen characteristics, motility parameters, and kinematic parameters between Wagyu and Bali bulls revealed no significant differences. The seminal plasma protein concentrations in Bali bulls and Wagyu did not show a statistically significant difference. The sperm protein concentration in Bali bulls was significantly higher compared to Wagyu. Seminal plasma analysis of Bali bulls showed a diverse protein profile and Wagyu semen plasma had fewer bands, reflecting breed-specific differences. In contrast, sperm analysis of Bali bulls and Wagyu consistently showed heavy protein bands on sperm function and viability.

Conclusion:
Bali bulls showed greater variation in spermatozoa protein than Wagyu, with protein differences at molecular weights of 60–63 kDa, 35 kDa, and 18–20 kDa. In addition, a positive correlation was found between the number of motile spermatozoa and the number of straws per ejaculate.

Key words: Bali cattle, Electrophoretic, Sperm, Seminal plasma, Wagyu cattle