Differences in preservation of canine chilled semen using simple sperm washing, single-layer centrifugation and modified swim-up preparation techniques

This study compared the efficacy of simple sperm washing (SW), single-layer centrifugation (SLC) and modified swim-up (SU) techniques in the preparation of dog spermatozoa for cooling. Eighteen ejaculates, collected from three dogs (six per dog), were pooled (three ejaculates per pool) and divided into three aliquots: (1) one aliquot was washed and cooled at 5°C for 72 h, considered as control (SW-control), (2) the second aliquot was selected by SLC through Androcoll-C and subsequently cooled in the same way as the SW-control samples (SLC-AC) and (3) the last aliquot was selected by a modified SU method with Androcoll-C and cooled as mentioned above (SU-AC). Assessment of sperm motility, sperm morphology, sperm membrane integrity and acrosome integrity were performed on aliquots of fresh semen and chilled-rewarmed samples. Sperm membrane integrity and progressive motility were significantly (P < 0.05) improved by SU-AC compared with SW-control. Morphological sperm abnormalities decreased significantly (P < 0.001) in SLC-AC samples compared with SW-control samples. These sperm variables did not differ between SLC-AC and SU-AC methods (P > 0.05). The recovery rates were not significantly (P > 0.05) different between SW-control, SLC-AC and SU-AC samples. Our results confirm that SU-AC may be a successful method for the preparation of dog spermatozoa for cooling.