The sperm membrane proteins (SMP) and seminal plasma proteins (SPP) were analyzed and characterized in freshly ejaculated semen of 14 crossbred cattle bulls. The protein content and profile were correlated to percent swollen spermatozoa in Hypo-osmotic swelling (HOS) buffer and freezability of semen. Higher amount of extraction of sperm membrane proteins and low rate of freezability and HOS positive spermatozoa in bull # 5,6,12 and 13 indicated low sperm membrane integrity in these bulls. The presence of 35 kDa and 220 kDa proteins in the SME of bulls with higher rate of semen freezability and HOS positive spermatozoa can be correlated to the good quality/fertility of semen. The presence of >240 kDa, 130 kDa and 220 kDa poteins in SP of bulls with lower-, higher- and non freezability of semen respectively can also be correlated to the rate of fertility of bulls.
