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 degrees 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 degrees C versus 24 degrees 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 degrees C, with benefits for post-thaw sperm motility and membrane integrity.