Seminal Plasma Proteins as Biomarkers of Fertility and Semen Traits in Egyptian Barki Rams

The objective of this study was to identify seminal plasma proteins associated with semen traits (mass motility (MM; %), live sperm (LS; %), abnormal sperm (AS; %), hypo-osmotic swelling test (Host; %), pH, colour, viscosity (Visco), ejaculate volume (VOL; ml), normal chromatin (NC; %), live sperm with reacted acrosome (LR; %), live sperm with unreacted acrosome (LU; %), dead sperm with reacted acrosome (DR; %), dead sperm with unreacted acrosome  (DU; %)) in Egyptian Barki rams. Depending on MM%, the animals were divided into three different groups (high (≥ 80% MM), medium (50-80% MM) and low-fertility (≤50% MM) group). The seminal plasma proteins were separated using one-dimensional sodium dodecyl sulfate polyacrylamide gel (SDS-PAGE) electrophoresis technique based on their molecular weight. The actual means for MM, LS, AS, Host, pH, colour, Visco, VOL, NC, LR, LU, DR and DU were 69.93%, 94.40%, 6.76%, 20.14%, 6.94, 3.30, 3.04, 0.75 mL, 53.52%, 44%, 15.78%, 19.36% and 20.86%, respectively. The correlation coefficients between MM and each of LS (0.61) and NC (0.89) were highly positive and significant (P<0.05). Semen samples displayed a total of 8 distinct protein bands in the SDS-PAGE of seminal plasma proteins. The identified protein bands ranged in molecular weight from 14 to 248 kDa. The high and medium fertility ram groups showed six of the bands. However, all eight protein bands were seen in the group of low-fertility rams. It is notable that the two bands solely identified in this group are those with molecular weights of 29 and 35 kDa. Negative and high correlations (P<0.05) were observed between these two bands and each of MM and LS, these correlations were -0.87 and -0.36 for the 29 kDa band and were -0.62 and -0.56 for the 35 kDa band, respectively. The reduced motility and low fertility of the rams in this group may be caused by these two bands of protein. In contrast, there were positive and significant correlation between the bands of 14 kDa, 25 kDa, and 248 kDa and MM, LS, NC, and LR (P<0.05). Relevant correlations between mass motility and other seminal characteristics were found in Barki rams. Potential seminal plasma proteins have identified as biomarkers for sperm mass motility and other related seminal and fertility associated traits.