Effect of the extender medium and the cooling and freezing curves over the sperm cell in Colombian creole horses

The aim was to analyze the parameters of motility, vigor, morphology and integrity of the plasma membrane for each of the cryoprotectans. Each eyaculated was divided into two equal aliquots. One half received dimethylformamide (5%) and the other half received glycerol (5%) as cryoprotectans. The protocol was performed with a cooling curve of 5ºC for 120 minutes, and exposure to nitrogen vapor for 15 minutes before being submerged in liquid nitrogen. Sperm viability (motility) was assessed by a thermal resistance test, the morphology of cells was evaluated by setting the semen in saline formalin and the integrity of the plasma membrane of the sperm tail by hyposmotic test. In respect to the parameters the post-thawing evaluation of the semen displayed no significant difference (p>0.05) between the two cryoprotectans. The results allow us to conclude that the use of extensor medium INRA 82, modified with sugar associated with skim milk and addition of 2% egg yolk and moderate cooling curve of 5ºC for 120 minutes shows a beneficial effect on sperm parameters in post-thaw period independently of the cryoprotectant used in the colombian criollo horses