Restrepo Betancur, GiovanniGómez Oquendo, JorgeVásquez Araque, Neil2012-05-292012-05-2920111794-4449http://hdl.handle.net/10567/375Introduction. Several factors influence the fertilizing capacity of cryopreserved canine semen. Structural alterations and the osmotic and toxic effects on sperm have focused interest on developing new cryopreservation and cryoprotection techniques with a bigger potential for conserving the semen´s fertilization capacity. Objective. To compare the effect of fast freezing with glycerol and dimethylformamide on the post-freezing quality of canine semen. Materials and methods. In a cryopreservation process by fast freezing, four treatments were implemented (glycerol at 3% and 5%, y dimethylformamide at 3% and 5%). After thawing, individual mobility, sperm morphology and the membrane´s integrity of sperm were evaluated. The statistic evaluation was made by the use of a variance analysis and a Fisher´s minimal significant difference test. Results. For the individual mobility, a superiority was found for the 5% glycerol (58%±7.8) over 5% DMF (44.5%±17.7), 3% glycerol (18%±10.1), and 3% DMF (11.8%±10.5). For the membrane´s integrity, 5%DMF had the highest media value (33.4%±9.7), above 3% glycerol (27.5%±4.3) y 3% DMF (24.2%±5.3), but it had no statistic difference over 5% glycerol (31.4%±3.8). For the sperm morphology, no statistic difference was found between 5% glycerol (67%±11.9), 3% glycerol (65.6±12.5), and 5%DMF (60%±16.5), but there was a difference between these and 3% DMF (50.1%±18.3). Conclusions. Glycerol and DMF, in 5% concentrations, provide a similar protection to semen during fast freezing cryopreservation.esCriopreservaciónCorporación Universitaria LasallistaCrioprotectoresSemen caninoSemen - CriopreservaciónGlicerolDimetilformamidaArticle