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Effects of the Inclusion of Equex STM into Tris-Based Extender on the Motility of Dog Spermatozoa Incubated at 5°C


Author’s address (correspondence address): Dr Wojciech Niżański, Department and Clinic of Reproduction, Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Pl. Grunwaldzki 49, 50-366 Wrocław, Poland. E-mail:


The aim of this study was to estimate the effects of Equex STM on sperm motion characteristics in chilled dog semen extended in Tris-based diluent. Thirty-two ejaculates were collected from 12 proven German shepherd stud dogs. The sperm-rich fractions were diluted in Tris-based extender with 1% (v/v) Equex STM (sample A) and in Tris-based extender with no addition of detergent (sample B). The extended semen was incubated for 240 h at 5°C and the motility parameters were evaluated by CASA system at 24-h intervals. Addition of Equex STM to Tris-based extender led to an initial activation of motion activity of spermatozoa, followed by a rapid decrease, shortening the lifespan of spermatozoa incubated at 5°C. Computer-assisted sperm analysis clearly showed that Equex STM-induced changes of sperm motion characteristics resemble the hyperactivation (HA) of spermatozoa associated with the capacitation process.