Qualitative and Quantitative Estimation of Osteopontin in Bull Semen and its Effect on Sperm Quality Parameters and Fertility Rate In vivo

Background: Osteopontin plays a crucial role in fertilization and subsequent embryonic development. Methods: The fresh semen samples were collected from crossbred Jersey and Haryana breeding bulls. The proteins in the seminal plasma and sperm membrane were precipitated and analysed by SDS-PAGE followed by western blotting. Based on the concentration of osteopontin in the seminal plasma, the bulls were grouped as high (>= 20 pg/ml), medium (10-20 pg/ml) and low (<= 10 pg/ml) OPN groups. Result: Total 13 and 14 different proteins were identified in the seminal plasma and sperm membrane, respectively. The sperm velocity parameters (straight line velocity and straightness) and functional membrane integrity showed significant difference among high, medium and low OPN groups. Significant difference (P<0.05) was observed in malondialdehyde, SOD and glutathione reductase levels. Bulls which are having high osteopontin concentration in the semen had less sperm abnormality, less apoptotic cells, better resistance to cryopreservation, less damaged chromatin and higher conception rate (64.80 +/- 1.09) than bulls having low osteopontin concentration in their semen. Therefore, osteopontin may be a valuable protein marker to predict fertility in bulls.