Investigations on the Role of the 22-24 kDa Seminal Plasma Protein in Bull Breed Fertility and Semen Quality through Proteomics

Abstract

Seminal plasma contains proteins that serve as a protective shield for sperm. These proteins potentially play an important role both in sperm quality and fertility. This study aimed to identify the proteins in seminal plasma that can significantly improve the quality of semen and enhance reproductive performance of bulls of different breeds. Semen samples were collected weekly for five weeks from each of five bulls of six breeds (Limousin, Friesian Holstein, Wagyu, Angus, Ongole, and Brahman). The quality of the semen was assessed, and seminal plasma proteins were identified using a proteomic approach through SDS-PAGE and LC-MS/MS analysis. The semen quality parameters were analyzed using two-way ANOVA, and protein identification was conducted using UniProt. Results showed that sperm quality was significantly different (P<0.05) among the breeds, whereas there was no difference among weeks of semen collection. The LC-MS/MS analysis revealed that Ongole bulls had the highest number (18) of seminal plasma proteins, while the Wagyu had the lowest number of only five proteins. In summary, the ejaculate of six bull breeds contained a wide range of 22-24kDa proteins, with a total of 36 different proteins. Four identical proteins were detected in all breeds, which were seminal ribonuclease (RNASE1-2), acrosin-binding protein (ACRBP), T-cell surface glycoprotein CD3 zeta chain (CD247) and renin receptor (ATP6AP2). These seminal plasma proteins were assessed to show strong correlation with sperm fertility. Therefore, they have the potential to be used as biomarkers for the evaluation of bull fertility.