Dialysis of bovine semen and its effect on fresh and freeze-thawed spermatozoa

The effect of the removal of the low-molecular-weight fraction (LMWF, less than 12,000-14,000 Da) from the seminal plasma present in extended semen by dialysis and by centrifugation (1,376g for 20 min at 5 degrees C) were compared with the current methods of freezing bovine semen. Significantly higher sperm post-thaw motility (P less than 0.05) was obtained in the dialyzed samples than with the other two methods. The appropriate time and temperature for dialysis of semen was also studied. Semen aliquots were dialyzed (1:50, retentate:dialysate) for 30 min, 1 or 2 hr at 5 degrees C, and during the cooling process from 37 to 5 degrees C over a 2-hr period. Superior sperm motility (P less than 0.05) in prefreeze and post-thawed samples was observed when semen was dialyzed for 1 or 2 hr during the cooling process as compared with that of semen dialyzed at 5 degrees C. A third experiment was conducted to establish the effect of the use of dialysis bags of different molecular weight cutoffs (MWCO) on sperm motility. Semen samples were dialyzed (1:50) during the cooling process in dialysis bags of 1,000, 3,500, 6,000-8,000, 12,000-14,000, 25,000, and 50,000 MWCO. No statistical differences (P greater than 0.05) in sperm post-thaw motility were found after evaluation of the number of cells that passed through the Sephadex filter and all the dialyzed values obtained were significantly (P less than 0.05) superior to the results obtained with no dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)