Evaluation of amides and centrifugation temperature in boar semen cryopreservation

Two experiments were conducted to evaluate the use of amides as cryoprotectants and two centrifugation temperatures (15 or 24 °C) in boar semen cryopreservation protocols. Semen was diluted in BTS, cooled centrifuged, added to cooling extenders, followed by the addition of various cryoprotectants. In experiment 1, mean (±S.E.M.) sperm motility for 5% dimethylformamide (DMF; 50.6 ± 1.9%) and 5% dimethylacetamide (DMA; 53.8 ± 1.7%) were superior (P < 0.05) to 5% methylformamide (MF; 43.2 ± 2.4%) and 3% glycerol (GLY; 38.1 ± 2.3%), with no significant difference between MF and GLY. Sperm membrane integrity was higher (P < 0.05) for DMA than for MF or GLY (50.9 ± 1.9, 43.3 ± 2.5, and 34.5 ± 2.8%, respectively). Sperm membrane integrity was higher in DMF (47.9 ± 2.1%) than in glycerol (34.5 ± 2.8%, P < 0.05), but was similar to other treatments (P > 0.05). In experiment 2, we tested MF, DMF, and DMA at 3, 5, and 7%. Sperm motility and membrane integrity were higher for 5% DMA (53.8 ± 1.7 and 50.9 ± 1.9%) and 5% DMF (50.6 ± 1.9 and 47.9 ± 2.1%), in comparison with 7% DMF and all MF concentrations (P < 0.05). For sperm motility and membrane integrity, 5% DMA exceeded (P < 0.05) 3% DM, with greater membrane integrity than 3% DMF (P < 0.05). In both experiments, sperm motility and membrane integrity were superior at 15 °C versus 24 °C (P < 0.05), with no interaction between centrifugation temperature and treatments (P > 0.05). In conclusion, boar semen was successfully cryopreserved by replacement of glycerol with amides (especially 5% DMA) and centrifugation at 15 °C, with benefits for post-thaw sperm motility and membrane integrity.