The potential of sperm bovine protamine as a protein marker of semen production and quality at the National Artificial Insemination Center of Indonesia

Background and Aim: Protamine (PRM) is the major protein in the sperm nucleus and plays an essential role in its normal function. Moreover, PRM has great potential as a protein marker of semen production and quality. This study aimed to assess the potential of sperm bovine PRM as a protein marker of semen production and quality in bulls at the National Artificial Insemination (AI) Center of Indonesia. Materials and Methods: The semen production capacity of each bull was collected from frozen semen production data at the Singosari AI Center for 6 months, and was then divided into two groups (high and low). A total of 440 frozen semen straws from six Limousin (LIM), six Friesian Holstein (FH), six Peranakan Ongole (PO), and four Aceh bulls aged 4-5 years were used in the study. The frozen semen was used to measure the concentration of PRM1, PRM2, and PRM3 using the enzyme immunoassay method. The frozen semen was also used to assess the quality of the semen, including progressive motility (PM) through computer-assisted semen analysis, sperm viability through eosin–nigrosin analysis, and the DNA fragmentation index through Acridine Orange staining. Results: PRM1 was significantly higher in all bull breeds included in the study (p<0.00), followed by PRM2 (p<0.00) and PRM3 (p<0.00). PRM1 significantly affected semen production in LIM, FH, PO, and Aceh bulls (p<0.05). Moreover, PRM2 significantly affected semen production only in FH and Aceh bulls (p<0.05), whereas PRM3 affected this parameter in PO and Aceh bulls exclusively (p<0.05). Consistently and significantly, PRM1 was positively correlated with the PM and viability of sperm and negatively associated with its DNA fragmentation in LIM, FH, PO, and Aceh bulls (p<0.05; p<0.01). The correlation analysis between PRM2 and PRM3 and semen quality parameters varied across all bull breeds; some were positively and negatively correlated (p<0.05; p