SEMINAL PLASMA AFFECTS MEMBRANE INTEGRITY AND MOTILITY OF EQUINE SPERMATOZOA AFTER CRYOPRESERVATION

Effects of seminal plasma on post-thaw motility and membrane integrity of cryopreserved horse spermatozoa were investigated. Carboxyfluoresc ein diacetate staining was used for the assessment of sperm membrane i ntegrity. Adding 30% of seminal plasma from stallions with high post-t haw sperm motility to ejaculates from stallions with low post-thaw spe rm motility increased progressive motility from 24.0 +/- 1.6 to 34.5 /- 1.9% (P<0.05) and membrane integrity from 27.0 +/- 2.1 to 34.3 +/- 2.3% membrane-intact spermatozoa (P<0.05). Conversely, the addition of seminal plasma from stallions with low post-thaw sperm motility to ej aculates from stallions with high post-thaw motility decreased progres sive motility from 36.0 +/- 1.6 to 30.0 +/- 2.7% (P<0.05) but did not induce changes in membrane integrity. Seminal plasma from stallions wi th opposite post-thaw motility therefore clearly influenced the resist ance of spermatozoa to the freezing and thawing process. We conclude t hat the individual composition of seminal plasma affects the suitabili ty of stallions for semen cryopreservation.