The limiting factor in the cryopreservation process of equine semen is related to the species, as they present a great variability in the ejaculate's characteristics after thawing. The aim of this study was to evaluate sperm viability after thawing, from Quarter Horse and Mangalarga Marchador stallions using two extenders (Botu-crio and Tris) in cryopreservation. To this end, we analyzed the physical characteristics of fresh semen, the sperm membrane functionality by the hypoosmotic swelling test (HOST), total motility and vigor by the Thermoresistance Test (TRT), progressive motility by a computerized system CASA (Computer-Assisted Semen Anlyses) and acrosomal membrane integrity and functionality of the mitochondria by epifluorescence microscopy. After thawing, the extender Botu-crio® better preserved motility, vigor and integrity of the plasma membrane. There was no significant difference between breeds for the thermoresistance test after twaing. Quarter Horse showed higher percentage of bigger defects in the sperm pathology analysis.
cryopreservation; equine; extender; semen