Restrepo Betancur, GiovanniUsuga Suarez, AlexandraMontoya Páez, Juan DavidDavid Celis, ÁlvaroAntonio Henao, Andrés2015-02-102015-02-1020141794-4449http://hdl.handle.net/10567/1224Introduction. The composition of the extenders for cryopreservation of stallion semen is crucial in cryotolerance and post-thaw fertilizing capacity of sperm cells. Objective. Evaluate two extenders for freezing the semen of Colombian creole stallions. Materials and methods. Semen of four Colombian creole stallions was cryopreserved by fast freezing protocol with Equipro® and Gent® extenders. Evaluation of sperm post-thaw motility was performed by a Sperm Class Analyzer system (SCA®) to examine total motility (TM), progressive motility (PM), velocity curvilinear (VCL), velocity straight line (VSL) and velocity average path (VAP). The sperm vitality (SV) and normal morphology (NM) were assessed by eosin-nigrosin staining; the plasmatic membrane integrity was determined by the hypo-osmotic swelling test (HOS). For statistical evaluation were adjusted generalized linear models (GLM) and the treatments averages were compared by the Tukey test. Associations between variables were assessed by Pearson correlation analysis. Results. Statistical difference (P≤ 0.05) was found for TM with averages of 50.9% ± 19.4% and 42.2% ± 15.1% for Equipro® and Gent®, respectively. Except for VSL no difference was found between the other evaluated parameters. There was a high association between motility parameters, vitality and membrane integrity. Conclusions. Equipro® extender produces superior post-thaw total motility rates than Gent® extender in sperm of Colombian creole stallions.esCorporación Universitaria LasallistaCaballo Criollo ColombianoCaballos - Mejoramiento de la especieCaballos - ReproducciónBiotecnología reproductivaArticle